Materials Science Pune University MCQs
Materials Science Pune University MCQs
This set of Materials Science Interview Questions and Answers focuses on “Classification of Materials”.
1. In terms of which of the following properties, metals are better than ceramics?
a) Hardness
b) Ductility
c) Toughness
d) Yield Strength
Answer: b
Explanation: Generally ceramics have equal or better hardness, toughness and yield strength but are highly susceptible to plastic deformation. Even a small stress beyond their yield point leads to fracture.
2. Steels mainly contain iron and carbon. Under which of the following categories do they belong?
a) Metallic Solid
b) Polymer
c) Composites
d) Ceramics
Answer: a
Explanation: Since steels have very small amounts of carbon , they are considered iron alloy; hence metallic solid.
3. GFRP is an important composite. It stands for
a) Gelatin Fibre Reinforced Polymer
b) Graphite Fibre Reinforced Polymer
c) Germanium Fibre Reinforced Polymer
d) Glass Fibre Reinforced Polymer
Answer: d
Explanation: Glass Fibre Reinforced Polymer or commonly called fiberglass is a lightweight, high-strength, and corrosion-resistant industrial material.
4. Ceramics make excellent refractory materials. A material is said to be refractory if it:
a) resists the flow of electric current
b) has high refractive index
c) retains its strength at high temperatures
d) all of the mentioned
Answer: c
Explanation: Ceramics, which mainly consist of oxides, carbides and nitrides, can withstand very high temperatures; furnaces are generally lined with such ceramics.
5. Which of the following cannot be used as bio-materials?
a) Metals
b) Ceramics
c) Polymers
d) None of the mentioned
Answer: d
Explanation: Bio-materials are implanted into living bodies for replacement of damaged parts and hence, must be compatible with the body tissues and be non-toxic. As long as these criteria are met, all of the above materials – metals, ceramics, polymers and their combinations can be used as bio-materials.
6. Which of the following is true for polymers?
a) They have very high molecular mass
b) They do not have a linear stress-strain curve
c) They have high strength to mass ratio
d) All of the mentioned
Answer: d
Explanation: Polymeric molecules are aggregates of a large number of monomer units and possess high molecular mass. Hooke’s law generally does not apply to polymers as the stress developed is not directly proportional to deformation. Due to low densities, strength to mass ratio of polymers is often comparable to metals and ceramics.
7. Various isotopes of a given element have same:
a) Number of protons
b) Number of neutrons
c) Molar mass
d) Thermodynamic stability
Answer: a
Explanation: Isotopes of a given element have the same number of protons but not of neutrons which causes variation in molar mass. This also results in different p-n ratio, thus making one isotope more stable than other. For example, protium is stable but tritium is radioactive.
8. Calcium is an isobar of Argon. They differ in:
a) Atomic weight
b) Number of nucleons
c) Number of neutrons
d) None of the mentioned
Answer: c
Explanation: Isobars differ in a number of protons as well as that of neutrons but total number of nucleons is the same for all the isobars. Hence, isobars have the same atomic weight.
This set of Materials Science Questions and Answers for Campus interviews focuses on “Atomic Structure Terminology”.
1. Species with the same number of neutrons but the different number of protons are called:
a) Isotones
b) Isotopes
c) Isomers
d) Isobars
Answer: a
Explanation: Isotones are atoms of different elements having the same number of neutrons but different atomic and mass numbers. For e.g., Boron-12 and Carbon-12 are isotones each having 7 neutrons.
2. Atomic number of a species is the number of:
a) Neutrons
b) Protons
c) Valence electrons
d) Nucleons
Answer: b
Explanation: Atomic number or the number of protons is the property that differentiates atoms of one species from another. For e.g., atomic numbers of Hydrogen and Helium are 1 and 2 respectively.
3. Oxygen gas is denser than Carbon Dioxide gas?
a) True
b) False
Answer: b
Explanation: At any specified temperature, molar volume for every gas is the same. However, CO 2 has higher molar weight than O 2 which results in higher density.
4. Which of the following has the least number of atoms?
a) One gram of Hydrogen gas
b) One gram of Helium gas
c) One gram-mole of Oxygen gas
d) One gram-mole of Chlorine gas
Answer: b
Explanation: One gram-mole of any gas contains Avogadro’s number of atoms/molecules. Hence, one gram-mole of Hydrogen gas and Helium gas weigh two grams and three grams respectively. 1g H 2 = 1/2 g-mol H 2 ; 1g He = 1/3 g-mol He. Thus, one gram of Helium has the least number of atoms.
5. Which of the following is not a pure form of matter?
a) Element
b) Compound
c) Solution
d) Both Compound and Solution
Answer: c
Explanation: Different samples of the same element or compound will have an exactly same composition and hence both – element and compound are considered pure forms of matter.
6. Which if the following is not an SI unit?
a) Kilogram
b) Mole
c) Atomic Mass Unit
d) Coulomb
Answer: c
Explanation: Because the SI unit of mass is a kilogram.
7. One unified atomic mass unit equals to ____________
a) 1/12 of molar mass of Carbon
b) 1/16 of atomic mass of Oxygen
c) 1/2 of the molecular mass of Hydrogen
d) all of the mentioned
Answer: d
Explanation: 1 amu = 1/12 of atomic mass of carbon = 1/16 of the atomic mass of Oxygen = 1/2 of molecular mass of Hydrogen.
8. Avogadro’s number of water molecules occupy 22.4 liters of space at 273 K.
a) True
b) False
Answer: b
Explanation: Molar volume at 273 K is 22.4 liter, only for gases. However, at this temperature water does not exist as a gas.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Atomic Models”.
1. In the wave-mechanical model of an atom, degenerate energy levels have:
a) Equal energy
b) Equal number of electrons
c) Same shape
d) Electrons with the same spin
Answer: a
Explanation: Degenerate energy levels have equal energy. In an atom, the orbitals in the same subshell are degenerate in absence of an external magnetic field.
2. Paired electrons in an atom have equal values of all of the four quantum numbers.
a) True
b) False
Answer: b
Explanation: According to Pauli’s exclusion principle, no two electrons in an atom can have all four quantum numbers equal. Paired electrons have opposite spins.
3. Protons attract electrons. Then why do electrons not fall on the nucleus?
a) Neutrons repel the electrons
b) Electrons in ground state cannot radiate energy
c) At very small distances, protons repel electrons
d) Inner electrons repel those in outer orbitals
Answer: b
Explanation: In the ground state, electrons form standing waves. Standing waves are those in which energy is not transferred. Hence, electrons are bound to revolve around the nucleus with constant potential energy.
4. Number of atomic orbitals in nth shell is:
a) n 2
b) 2n 2
c) 2n + 1
d) n − 1
Answer: a
Explanation: Every shell contains n 2 orbitals and every orbital can accommodate a maximum of 2 electrons. Hence a maximum of 2n 2 electrons can reside in nth shell.
5. Electronic configuration of Cu is [Ar] 3d10 4s1. Which rule is violated in this configuration?
a) Aufbau Principle
b) Hund’s Rule of Maximum Multiplicity
c) Pauli’s Exclusion Principle
d) None of the mentioned
Answer: a
Explanation: According to the Aufbau principle, orbitals of lower energy are completely filled before electrons start occupying higher energy orbitals. But in copper, higher energy 3d is filled before lower energy 4s. Such violation of the Aufbau principle appears in about 20 elements.
6. When an electron shifts to an inner shell, it:
a) Absorbs photon
b) Emits a photon
c) Emits a positron
d) Absorbs a positron
Answer: b
Explanation: Generally, lower potential energy means more stability. Excited electrons lose energy in the form of photons to shift to stable empty inner shells. Positron is anti-particle of an electron.
7. Around 1911, Rutherford suggested a planetary model of atomic structure. Which of the following was not a proposition of this model?
a) Electrons revolve in circular orbits around the nucleus
b) Nucleus consists of protons and neutrons
c) Mass of atom is concentrated in the nucleus
d) Most of the volume in an atom is void
Answer: b
Explanation: Neutrons were not discovered by then. Rutherford only suggested that the nucleus has a positive charge, but did not comment on its structure.
8. Which of the Bohr’s postulates was incorrect?
a) Energy of electrons is quantized
b) Momentum of electrons is quantized
c) Electrons release energy when shifting from excited state to ground state
d) Electrons revolve around the nucleus in fixed circular orbits
Answer: d
Explanation: Heisenberg uncertainty principle implies that exact position and momentum of electrons cannot be known with certainty and hence, definite circular paths are not feasible. Certain regions around the nucleus have a high probability of the existence of electrons.
9. 4f orbital has higher energy than 5p.
a) True
b) False
Answer: a
Explanation: Sum of principal and azimuthal quantum numbers for 4f is 7 and that for 5p is 6. As a general rule, higher the sum, higher is the energy.
10. Which of the following orbitals do not exist?
a) 3p
b) 4s
c) 2s
d) 3f
Answer: d
Explanation: For principal quantum number 3, only possible values of azimuthal quantum number are 0, 1, and 2. Azimuthal quantum number of an f-orbital is 3.
This set of Materials Science Questions and Answers for Freshers focuses on “Atomic Bondings in Solids”.
1. Which of the following is a secondary bond?
a) Metallic bond
b) Hydrogen bond
c) Covalent bond
d) Ionic bond
Answer: b
Explanation: Metallic, covalent, and ionic bonds are strong in nature, hence primary; hydrogen bond has comparatively lower bond energies; hence secondary.
2. VSEPR stands for Valence Shell Electron Pair Repulsion. This theory helps us predict:
a) Bond angles
b) Bond length
c) Electron energy
d) Shell radius
Answer: a
Explanation: VSEPR theory implies that electrons in valence shell arrange themselves in a manner so as to experience minimum repulsion from other electrons. For e.g., in a CH 4 molecule, all the bonds are symmetrically arranged at approximately 109°.
3. In water, the bond angle between the H-O H-O bond is less than 109° Why?
a) The H atoms attract each other
b) Oxygen atom is much larger than Hydrogen atoms
c) Lone pair-bond pair repulsion is greater than bond pair-bond pair repulsion
d) VSEPR theory does not apply for planar molecules like water
Answer: c
Explanation: Bond angle is 109° for symmetric molecules like methane. However, it is known that repulsion between a lone pair and a bond pair is more than that between two bond pairs. Hence, bond angle is reduced from 109° so as to experience minimum repulsion from lone pairs.
4. For covalent molecules, van der Waals radius is always greater than a covalent radius.
a) True
b) False
Answer: a
Explanation: Van der Waals radius is half the internuclear distance between two non-bonded atoms on their closest approach whereas covalent radius is half the bond length of a homo-nuclear molecule. Since the distance between two bonded atoms is less than non-bonded atoms, hence the answer.
5. If E1 is the bond enthalpy of a sigma-bond and E2 is that of a pi-bond, then:
a) E1 > E2
b) E1 = E2
c) E1 < E2
d) Can’t be predicted
Answer: a
Explanation: Since the overlap of orbitals in a sigma-bond is along the internuclear axis contrary to sideways overlap in pi-bonds, the bonding is more effective in a sigma-bond. Hence, E1 > E2. Though, the total energy of a double bond is more than a single bond)
6. Which of the following molecules is non-linear?
a) Hbr
b) CO 2
c) C 2 H 2
d) H 2 S
Answer: d
Explanation: H 2 S is non-linear due to presence of lone pairs on S atom. Hbr being a binary molecule is linear. Double bonds in CO 2 and C 2 H 2 also leads to linear geometry.
7. With an increase in bond length, bond energy:
a) increases
b) decreases
c) may either increase or decrease
d) does not change
Answer: b
Explanation: The coulombic force of attraction is inversely proportional to the square of a distance between the charges. As the internuclear distance in a bond increases, the force of attraction between nuclei and electrons decreases.
8. sp 3 hybridization is present in which of the following molecules?
a) BeCl 2
b) H 2 O
c) C 2 H 4
d) BCl 3
Answer: b
Explanation: Hybridization takes place between one 2s and three 2p orbitals of Oxygen so as to minimize electronic repulsion. BeCl 2 , C 2 H 4 , and BCl 3 have sp, sp 2 , and sp 2 hybridization respectively.
9. Which of the following is the correct order for bonding energies of molecular orbitals?
a) σ1s < σ2s < σ*2s < σ*1s
b) σ1s < σ2s < σ*1s < σ*2s
c) σ1s < σ*1s < σ2s < σ*2s
d) none of the mentioned
Answer: c
Explanation: Energy of bonding MO is less than that of anti-bonding MO formed from same atomic orbitals. Also, MO formed from atomic orbitals of higher energy possess higher energy.
10. Which of the following molecules is diamagnetic?
a) O 2
b) CO
c) \
NO
Answer: b
Explanation: Out of the above species, only CO does not have unpaired electrons. Others have partially filled molecular orbitals and hence are attracted by external magnetic fields.
This set of Materials Science Interview Questions and Answers for freshers focuses on “Periodic Table of Elements”.
1. Elements in the same column of the periodic table have:
a) Similar valence shell electron configuration
b) Same value of highest principal quantum number
c) Same number of nucleons
d) All of the mentioned
Answer: a
Explanation: The elements having similar valence shell electrons have similar chemical properties like reactivity, nature of bonds in their molecules etc. Hence in the modern periodic table, they were grouped in vertical columns called ‘groups’.
2. As we move down a group, electronegativity of elements generally:
a) Increases
b) Decreases
c) Increases and then decreases
d) Decreases and then increases
Answer: b
Explanation: As we move down a group, atomic size increases which means that the valence electrons are much farther from the nucleus and hence experience less force of attraction. Hence the electronegativity decreases down the group.
3. How many periods are there in a modern periodic table?
a) 5
b) 6
c) 7
d) 8
Answer: c
Explanation: Modern periodic table places elements having the same maximum principal quantum number in one period. There are seven periods, though the seventh period consists of many unstable artificial elements.
4. Temporary IUPAC systematic symbol for the synthetic element 117 is:
a) Uuh
b) Uns
c) Uus
d) Une
Answer: c
Explanation: IUPAC has assigned temporary systematic name Ununseptium [=Un +un + sept + ium] to the element with atomic number 117. It belongs to group 17 of the periodic table and is predicted to be a halogen. As of 2015, its discovery has not been officially confirmed.
5. There are seventeen non-metals in the periodic table. Unlike metals in the same period, they have higher:
a) Atomic number
b) Atomic size
c) Electropositivity
d) All of the mentioned
Answer: a
Explanation: Non-metals are located at the right end of their respective periods. As we move from left to right in a period or from top to bottom in a group, atomic number increases. Due to increasing charge on the nucleus, atomic size also decreases on moving right in a period. This is also the reason of increasing electronegativity or decreasing electropositivity.
6. d-block elements generally show multiple oxidation states. An exception to this is:
a) Zinc
b) Mercury
c) Copper
d) None of the mentioned
Answer: a
Explanation: Due to a small increase in successive ionization enthalpies, most d-block elements exist in multiple oxidation states. However, Zn compounds are very rare and the ion exists in a dimeric form.
7. Uranium and Thorium are two important elements in the nuclear power industry. In which block of the modern periodic table are they placed?
a) s-block
b) p-block
c) d-block
d) f-block
Answer: d
Explanation: Ground state Uranium and Thorium atoms have partially or totally empty 5f-orbitals. They are members of the actinide family and their naturally occurring isotopes are radioactive.
8. Moving down a group, which of the following properties generally diminishes?
a) Electronegativity
b) Metallic character
c) Atomic radius
d) Molar mass
Answer: a
Explanation: Due to the addition of one shell on moving down a group, the neighbourhood of the atom is better shielded by the electrons from an attractive pull of the nucleus.
9. Radon is the sixth member of group 18 of the modern periodic table. Unlike other members of this group, Radon:
a) is solid near room temperature
b) is radioactive
c) possess high chemical reactivity
d) all of the mentioned
Answer: b
Explanation: Radon is a radioactive noble-gas at room temperatures. It is one of densest gases and the only naturally occurring radioactive gas. However, its daughter nuclei are solids. Not many compounds of Radon are known.
10. Ionization energy decreases down the group. It is the energy required by an isolated gaseous atom to form an anion.
a) True
b) False
Answer: b
Explanation: Ionization energy is the energy required by an isolated gaseous atom to lose the least tightly bound electron to form a cation. It decreases down the group as atomic size increases.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Properties of Crystals”.
1. Allotropes differ in which of the following properties:
a) Atomic Number
b) Atomic Mass
c) Crystal Structure
d) Electronegativity
Answer: c
Explanation: Allotropes are different crystalline structures of the same element. Hence, they have the same atomic number, atomic mass and electronegativity. For e.g., graphite and diamond are allotropes of carbon.
2. Co-ordination number of a crystalline solid is:
a) Number of particles in the unit cell
b) Number of nearest neighbours of a particle
c) Number of octahedral voids in a unit cell
d) Number of tetrahedral voids in a unit cell
Answer: b
Explanation: Coordination number of a crystal structure is the number of particles with which a given particle is in direct contact.
3. Packing efficiency of a crystal structure is the ratio of:
a) Volume occupied by particles to the total volume of the unit cell
b) Volume occupied by particles to that by voids
c) Total volume of the unit cell to the volume occupied by particles
d) Volume occupied by voids to that by particles
Answer: a
Explanation: Packing efficiency represents the fraction of the unit cell volume that is utilized to hold the particles.
4. HCP and BCC are called close-packed structures. Close packed structures have:
a) Highest packing efficiency
b) Highest void fraction
c) Highest density
d) All of the mentioned
Answer: a
Explanation: Due to the largest number of particles in a unit cell, close-packed structures have the highest packing efficiency and hence, lest void fraction. Density is NOT a property of the crystal structure but the substance and depends also on molar mass.
5. An octahedral void is surrounded by:
a) 8 atoms
b) 18 atoms
c) 6 atoms
d) 16 atoms
Answer: c
Explanation: An octahedral void resembles a regular octahedron with atoms situated at all the six vertices.
6. Which of the following is a property of amorphous solids?
a) Sharp melting point
b) Isotropy
c) Long range order
d) Definite heat of fusion
Answer: b
Explanation: Due to irregularity in structure, the average of physical properties like density, thermal and electrical conductivity etc. is same along any direction for a particular amorphous solid.
7. Which of the following is a crystalline solid?
a) Copper wire
b) Glass bottle
c) Polythene bag
d) Rubber ball
Answer: a
Explanation: Copper wires are made of crystalline copper. In fact, most metallic objects are crystalline. However, research for the large-scale production of amorphous metals is in progress.
8. The smallest portion of a crystal which when repeated in different directions generates the entire crystal is called:
a) Lattice points
b) Crystal lattice
c) Unit cell
d) None of the mentioned
Answer: c
Explanation: Unit cell is the smallest unit of a crystal which repeats itself to generate the crystal. Lattice point represents the centres of atoms in a unit cell. Crystal lattice refers to the entire structure of a crystalline solid.
9. Which of the following is not a property of metal glass?
a) Transparent
b) Poor thermal conductivity
c) High magnetic susceptibility
d) None of the mentioned
Answer: a
Explanation: Metal glass is a form of metal which like glass, is amorphous but not transparent. Most of the metal glasses are alloys, having high yield strength and high elastic strain limits. High magnetic susceptibility, low coercivity and comparatively higher electrical resistance than their crystalline counterparts make them an ideal material for power transformers.
10. Grain boundaries are one of the causes of corrosion of metals?
a) True
b) False
Answer: a
Explanation: Grain boundaries are the regions that separate two grains in polycrystalline metallic solids. The absence of properly defined structure results in residual stresses. Hence, grain boundaries are the weak spots in the structure and are often the site of a fracture.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Bravais Lattices”.
1. Most Bravais lattices are of the type:
a) Primitive unit cell
b) Body centered unit cell
c) End centered unit cell
d) Face centered unit cell
Answer: a
Explanation: Out of 14 naturally occurring Bravais lattices, 7 are primitive. Remaining seven consists of 3 body centered, 2 face centered and 2 end centered unit cells.
2. In which of the following Bravais lattices, not all axial angles are right angles?
a) Tetragonal
b) Rhombohedral
c) Orthorhombic
d) Cubic
Answer: b
Explanation: A rhombohedral is a prism whose base is shaped as a non-square rhombus. Hence two of its six faces are rhombuses while others are rectangles. This results in a geometry for which two of the axial angles are right angles but the third is not.
3. Which of the following Bravais lattices exist as face centered unit cell?
a) Orthorhombic
b) Monoclinic
c) Tetragonal
d) None of the mentioned
Answer: a
Explanation: Orthorhombic lattice exists as all four types of unit cells. Besides primitive cell, monoclinic lattice exists only as end centered cell while tetragonal exists only as body centered lattices.
4. Coordination number for an ideal BCC metallic crystal is:
a) 8
b) 6
c) 12
d) Varies for different metals
Answer: a
Explanation: Consider the atom at the body center. It is touched by all the atoms present at the vertices of the cubic unit cell. We know that a cube has 8 vertices.
5. Number of particles in a primitive cubic unit cell is:
a) 1
b) 2
c) 3
d) 4
Answer: a
Explanation: In a primitive cubic cell, 8 atoms are present at the eight vertices of the cube. However, each atom is shared by eight unit cells. Hence, only one-eighth of each of the eight atoms is present in one primitive cubic cell.
6. In which of the following Bravais lattices none of the sides are equal?
a) Triclinic
b) Monoclinic
c) Orthorhombic
d) All of the mentioned
Answer: d
Explanation: Each of the above mentioned lattices have all axial distances unequal. Moreover, triclinic, monoclinic, and orthorhombic lattices have none, two and all axial angles as right angles respectively.
7. Graphite is a common allotrope of Carbon. Its crystal structure is:
a) Cubic
b) Monoclinic
c) Orthorhombic
d) Hexagonal
Answer: d
Explanation: Graphite crystals consist of several planar layers of Carbon atoms arranged in interconnected hexagonal rings. Each atom makes three &sigma bonds and one &pi bond. VSEPR theory predicts a trigonal planar molecular structure with respect to each Carbon atom.
8. Which of the following lattices has the highest void fraction?
a) Hexagonal close packed
b) Body centered cubic
c) Face centered cubic
d) Primitive cubic
Answer: d
Explanation: Void fraction = 1 − packing efficiency
Since primitive cubic unit cell has least packing efficiency out of those mentioned above, hence it has the highest void fraction of 0.48 or 48 %.
9. Which of the following unit cells do not exist for tetragonal lattices?
a) Primitive centered unit cell
b) Body centered unit cell
c) Face centered unit cell
d) All of the mentioned exist
Answer: c
Explanation: Tetragonal lattices exist only in primitive and body centered unit cells. Face centered unit cells occur only for cubic and orthorhombic lattices.
10. Most unsymmetrical Bravais lattice in terms of axial distances and angles is:
a) Monoclinic
b) Triclinic
c) Rhombohedral
d) Hexagonal
Answer: b
Explanation: For triclinic lattice, none of the adjacent sides are equal in length; neither are any axial angles equal. Hydrated copper sulphate and boric acid have triclinic crystals.
This set of Materials Science Questions and Answers for Experienced people focuses on “FCC and HCP Metallic Crystals”.
1. Coordination number of HCP and FCC lattices respectively are:
a) 12, 12
b) 4, 4
c) 12, 8
d) 8, 8
Answer: a
Explanation: Coordination number is the number of atoms that are in direct contact of any particular atom or it is the number of nearest neighbours.
2. Number of particles in one unit cell of HCP lattice is:
a) 1
b) 2
c) 4
d) 6
Answer: d
Explanation: Consider the top and bottom layers. One-sixth of each of the 12 atoms located at the vertices of the two hexagons belong to the cell. Also half of the atoms at the centre of each of the two hexagons are also part of the cell. Three more atoms are present between two hexagonal planes.
3. Standard axial ratio for metallic HCP lattice is 2√. It is the ratio of
a) Atomic radius to hexagon edge length
b) Hexagon height length to atomic radius
c) Atomic radius to hexagon height
d) None of the mentioned
Answer: d
Explanation: Ratio of the height of the hexagonal unit cell to its edge length is called the axial ratio, usually expressed as .
4. The void fraction is the ratio of unfilled volume to total volume of a structure. For ideal metallic FCC crystal, it is:
a) 0.22
b) 0.26
c) 0.32
d) 0.38
Answer: b
Explanation: Void fraction = 1 − packing efficiency
Packing efficiency for FCC lattice is 0.74 and hence, void fraction is 1 − 0.74.
5. If N is the number of tetrahedral voids in a close-packed structure, then the number of octahedral voids is:
a) N/4
b) 4N
c) 2N
d) N/2
Answer: d
Explanation: Tetrahedral voids are formed when triangular voids of one close-packed layer do not overlap while octahedral ones when they overlap. The above relation is valid for both ABAB type and ABCABC type packing.
6. An octahedral void is present at each edge of the FCC lattice. How much of each of these voids belong to each unit cell?
a) One-eighth
b) One-sixth
c) One-fourth
d) Half
Answer: c
Explanation: In a cubic lattice, each edge is shared by four adjacent cubes. Hence, the octahedral voids present at these edges are equally divided among the four cells.
7. The edge length of an FCC lattice is X times the atomic radius. Value of X is:
a) 2
b) 2√2
c) 4/√3
d) 3/√2
Answer: b
Explanation: In FCC unit cell, the atoms at face diagonal touch each other; thus diagonal is four times the atomic radius. Diagonal of the square faces is also equal to √ times of the edge length. Hence, √2a = 4r.
8. Density is the ratio of the mass of crystal to its volume. For a perfect FCC metallic crystal, the mass of a unit cell is 4 times M 0 . M 0 is:
a) specific mass
b) molar mass
c) atomic mass
d) none of the mentioned
Answer: c
Explanation: Mass of an ideal FCC metallic crystal unit cell is four times the atomic mass of the metal since there are four atoms per unit cell.
9. A maximum of 74% packing efficiency can be achieved for crystalline solids.
a) True
b) False
Answer: b
Explanation: 74% is the maximum packing efficiency for pure metallic crystals. However, if there are particles of two or more different sizes, greater packing efficiency is possible by filling the tetrahedral and octahedral voids.
10. Which of the following quantities is larger in HCP as compared to FCC if the constituting atoms are similar?
a) Number of particles per unit cell
b) Volume per unit cell
c) Mass per unit cell
d) All of the mentioned
Answer: d
Explanation: An HCP unit cell contains 6 atoms rather than only 4 present in FCC. Also, both structures are assumed to be comprised of similar atoms thus HCP being heavier. However, the HCP unit cell is also larger in volume than an FCC one such that both have same packing efficiency.
This set of Materials Science Questions and Answers for Entrance exams focuses on “Crystallographic Directions and Planes”.
1. Which of the following is not true for crystallographic axes?
a) They must be parallel to the edges of the unit cell
b) They must be perpendicular to each other
c) They must originate at one of the vertices of the cell
d) They form a right-handed co-ordinate system
Answer: b
Explanation: The axes must be parallel to the edges of the unit cell, which in case of some crystal systems like monoclinic, hexagonal etc. are not mutually perpendicular.
2. The point coordinate indices q, r, and s are multiples of:
a) Unit cell edge lengths
b) Distance between nearest neighbours
c) Cosine of angles between unit cell edges
d) None of the mentioned
Answer: a
Explanation: Point coordinate indices are the fractions which when multiplied by the corresponding unit cell edge lengths, provide the location of a given point in the crystallographic coordinate system.
3. The point coordinates of the vertex just opposite to the origin are
a) 0 0 0
b) 0 0 1
c) 0 1 1
d) 1 1 1
Answer: d
Explanation: Since the opposite vertex is located at distances equal to the edge lengths along the coordinate axes.
4. If x, y, and z are three positive axes of the crystallographic coordinate system with origin at point A, then which line points in the direction [1 0 1 ] ?
materials-science-questions-answers-entrance-exams-q4
a) AD
b) CH
c) FB
d) GE
Answer: c
Explanation: Moving 1 unit along positive x-axis, 0 units along positive y-axis, 1 unit along negative z-axis points in a direction parallel to line FB.
5. In the following diagram, what is the direction cosine of the line EB?
materials-science-questions-answers-entrance-exams-q4
a) [1 1 1 ]
b) [ 1 1 1 ]
c) [1 1 1]
d) [1 0 0]
Answer: a
Explanation: One can reach from point E to B by traversing 1 unit along each of positive x, negative y, and negative z-axis, where one unit along any axis equals the corresponding edge length.
6. In cubic crystals, crystallographic directions are arranged in families. Which of the following directions does not belong to the family <110>?
a) [1 0 1]
b) [ 1 1 0]
c) [ 1 0 1̅]
d) None of the mentioned
Answer: d
Explanation: Since the cubic lattice is symmetrical about all the three axes, the above directions are equivalent irrespective of order & sign and are part of same direction family.
7. Convert [2 1 1 1] from four-index system to three-index system.
a) [2 1 0]
b) [3 0 1]
c) [ 1 1 1]
d) [ 1 2 1]
Answer: b
Explanation: [u v t w] can be converted to [U V W] using the formula: i) U = 2u+v ii) V = 2v+u iii) W = w. Four-index systems are generally used for hexagonal lattices.
8. Miller indices of the hatched plane in the following figure are:
materials-science-questions-answers-entrance-exams-q8
a)
b)
c)
d)
Answer: a
Explanation: If a plane intercepts the coordinate axes at distances A, B, and C from the origin, then Miller indices are given by multiplying by a suitable factor so as to obtain integers.
9. Which of the following is a property of Miller indices?
a) They uniquely identify a plane
b) They are always positive
c) They are not fractions
d) None of the mentioned
Answer: c
Explanation: Two or more planes can have same Miller indices which can be negative, zero or positive depending on the intercept on the axes. If the ratios of intercepts to lattice constants come out be fractional, then they are scaled to lowest integers to be represented as Miller indices.
10. Miller indices for perpendicular planes are always the same.
a) True
b) False
Answer: b
Explanation: It is true only for cubic lattices. For other systems, there is no simple relationship between planes with the same Miller indices.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Bragg’s Law”.
1. X-rays have larger wavelengths than which of the following?
a) Gamma rays
b) Beta rays
c) Microwave
d) Visible light
Answer: a
Explanation: Larger wavelengths mean less energy. Only gamma rays have higher energy than x-rays. Beta rays are actually streaming of particles and have much less energy than x-rays.
2. X-ray diffraction patterns are used for studying crystal structure of solids because
a) They have very high energy, hence they can penetrate through solids
b) They are electromagnetic radiation, and hence do not interact with matter
c) Their wavelengths are comparable to inter-atomic distances
d) Their high frequency enables rapid analysis
Answer: c
Explanation: For diffraction to occur, the obstacle size should be comparable to the wavelength of the incident radiation.
3. For destructive interference to take place, the path difference between the two waves should be:
a) nλ
b) 2nλ
c) λ
d) λ
Answer: a
Explanation: Constructive interference occurs when the phase difference between two interfering waves is an integral multiple of 2π. Also, the ratio of path difference to wavelength equals that of phase difference to 2π.
4. Bragg’s law is not a sufficient condition for diffraction by crystalline solids.
a) True
b) False
Answer: a
Explanation: Atoms present at non-corner positions may result in out-of-phase scattering at Bragg angles.
5. The Miller indices h, k, and l of parallel planes in a BCC lattice should satisfy which of the following X-ray diffraction reflection rules?
a) h + k + l should be even
b) h, k, and l should all be either even or odd
c) h, k, and l should form Pythagoras triplet
d) all planes allow reflections
Answer: a
Explanation: If the sum of Miller indices becomes odd for a BCC lattice, destructive interference occurs.
6. Minimum interplanar spacing required for Bragg’s diffraction is:
a) λ/4
b) λ/2
c) λ
d) 2λ
Answer: b
Explanation: Maximum value of incident angle can be 90° for which sine is 1. Hence d = λ/2
7. Laue’s model pictures XRD as reflection from parallel crystalline planes. Reflection is different from refraction as:
a) diffraction occurs throughout the bulk
b) intensity of diffracted beams is less
c) diffraction in crystals occurs only at Bragg’s angles
d) all of the mentioned
Answer: d
Explanation: Reflection is a surface phenomenon, and large portions of the incident waves can be reflected. Moreover, reflection can occur at any angle of incidence whereas diffraction patterns occur only at Bragg’s angles.
8. In Bragg’s equation [nλ = 2.d.sinθ], θ is the angle between:
a) specimen surface and incident rays
b) normal to specimen surface and incident rays
c) parallel lattice surfaces d distance apart and incident rays
d) normal to parallel lattice surfaces d distance apart and incident rays
Answer: c
Explanation: In the following figure, one can easily deduce that the path difference between the two incident waves is 2.d.sinθ using simple trigonometry. materials-science-questions-answers-braggs-law-q8
9. In the powder method of XRD, the intensities of various bright lines are compared to determine the crystal structure. For simple cubic lattice the ratio of intensities at first two maxima are:
a) 1 ⁄ 2
b) 3 ⁄ 4
c) 1 ⁄ 2
d) None of the mentioned
Answer: a
Explanation: For simple cubic lattice, the intensities at subsequent maxima are in the ratio 1:2:3:4:5:6:8
10. K-alpha x-rays have shorter wavelengths than K-beta x-rays?
a) True
b) False
Answer: b
Explanation: K-alpha is formed from a transfer of electrons from L shell to K while K-beta result from M-to-K transition. Hence K-alpha lines have lower energy .
This set of Materials Science Multiple Choice Questions & Answers focuses on “Amorphous Solids”.
1. Which of the following properties is generally exhibited by amorphous solids?
a) Anisotropy
b) Glass-transition
c) Equal strength of all bonds
d) All of the mentioned
Answer: b
Explanation: Due to random organization of particles, amorphous solids have the same physical properties along all directions, or are isotropic. Random organization of particles also results in unequal bond strengths. Upon cooling, amorphous solids turn into a brittle glass-like state from a flexible rubber-like state. This is called glass-transition.
2. Metal glass was first prepared at:
a) California Institute of Technology
b) Massachusetts Institute of Technology
c) Technion
d) University of Michigan
Answer: a
Explanation: Metal glass or amorphous metal was reportedly first produced by W. Klement , Willens and Duwez in 1960 at Caltech. It was prepared by rapid cooling of molten metal alloys.
3. Polycrystalline solids are isotropic.
a) True
b) False
Answer: a
Explanation: Anisotropy is a characteristic behavior shown by ideal crystals. However, the presence of flaws like grain boundaries causes the solid to deviate from crystalline properties.
4. Metal glasses differ from their crystalline counterparts in many ways. Chief application of metal glasses include:
a) Bullet-proof glasses
b) Power transformers
c) Conducting wires
d) All of the mentioned
Answer: b
Explanation: Amorphous metals are not transparent and have relatively lower electrical conductivity. However, most metal glasses possess high magnetic susceptibility and low coercivity.
5. Consider the following cooling diagram for an amorphous solid.
materials-science-questions-answers-amorphous-solids-q5
Glass-transition temperature is represented as:
a) A
b) B
c) C
d) None of the mentioned
Answer: b
Explanation: An exact melting point does not exist for amorphous solids. An approximate glass-transition temperature is defined by extrapolating the cooling curve as shown.
6. Soda-lime glass is the most common type of glass. The component present in largest w/w percentage is:
a) SiO 2
b) Al 2 O 3
c) Na 2 O
d) CaO
Answer: a
Explanation: Glass inherits its transparency from crystalline SiO 2 , also called quartz. However, quartz has very high and narrow glass-transition. To overcome this, small amount of Na 2 is added. CaO is also added to prevent water-solubility imparted by soda.
7. Lead-oxide glass is called “crystal glass” because:
a) It contains crystalline Pb
b) It contains SiO 2 crystals
c) It contains PbO crystals
d) None of the mentioned
Answer: d
Explanation: Well, crystal glass is amorphous, not crystalline. This glass earns its name from its excellent decorative properties and high refractive index.
8. Crystallinity increases with increasing rate of cooling of a liquid.
a) True
b) False
Answer: b
Explanation: When a liquid is cooled rapidly, the particles get less time to move and arrange themselves in an orderly fashion and hence the crystallinity of the resulting solid decreases.
This set of Materials Science Interview Questions and Answers for Experienced people focuses on “Classification of Crystallographic Defects”.
1. Frenkel defect belongs to which of the following classes?
a) Point defect
b) Linear dislocation
c) Interfacial defect
d) Bulk defect
Answer: a
Explanation: Frenkel defect occurs when some of the smaller ions shift from their lattice point to interstitial positions.
2. The ratio of the number of vacancies to a total number of lattice points for a metal near melting temperature is of the order of 10 -4 . For lower temperatures, the ratio:
a) increases
b) decreases
c) remains the same
d) may increase or decrease depending on the metal
Answer: b
Explanation: At lower temperature, less energy is available in the system which means less number of atoms are able to leave their lattice sites to create vacancies.
3. Foreign species is present in which of the following defects?
a) Interstitial
b) Vacancy
c) Substitution
d) All of the mentioned
Answer: c
Explanation: In substitution defect, particles of other species having similar sizes replace the host particles in a lattice whereas interstitial defect occurs when particles of the same species are present at interstitial voids.
4. Edge dislocation and screw dislocation are linear crystalline defects.
a) True
b) False
Answer: a
Explanation: Edge dislocation and screw dislocations are linear crystalline defects or line defects.
5. Burger vectors are relevant to which of the following crystalline defects?
a) Point defects
b) Line defects
c) Interfacial defects
d) Bulk defects
Answer: b
Explanation: Burger vector denotes the magnitude and direction of a line defect.
6. Pores & cracks in crystalline solids can be classified as bulk defects.
a) True
b) False
Answer: a
Explanation: Pores and cracks are not localized to a particular point or edge, but have sizes much larger than atomic dimensions.
7. Ferromagnetic material shows strong para-magnetic behaviour due to the formation of domains. These domains belong to:
a) Point defects
b) Linear defects
c) Interfacial defects
d) Bulk defects
Answer: c
Explanation: In ferromagnetic materials, the alignment of magnetic dipoles vary across domain walls. These walls spread across large surfaces but have negligible thickness.
8. Electrical conductivity of the specimen is a requirement for which of the following microscopic examination techniques?
a) Optical microscopy
b) Transmission electron microscopy
c) Scanning electron microscopy
d) Scanning probe microscopy
Answer: c
Explanation: Non-conducting specimen will develop electrostatic charge due to an incident electron beam. This field tends to produce faults in the signal interpretation.
9. Which of the following point defects is non-stoichiometric in nature?
a) Schottky defect
b) Metal excess defect
c) Interstitial defect
d) Impurity defect
Answer: b
Explanation: When alkali halides are heated in an atmosphere of the constituent metal, halide ions diffuse to the surface to react with the vapour particles. This results in excess of cations over anions.
10. The solubility of solute in a solvent in a solid solution is governed by Hume-Rothery rules. The solubility is more if:
a) radii of solute are much smaller than that of solvent
b) solute an solvent have a similar crystal structure
c) solute has low valence
d) all of the mentioned
Answer: b
Explanation: For high solubility, the solute-solvent pair should have similar radii, crystal structure, and electronegativity. Moreover, for other factors being equal, a solute with higher valence is more soluble than one having lower valence.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Point Defects – 1”.
1. Which type of defect are point defects?
a) One dimensional defect
b) Zero dimensional defect
c) Two dimensional defect
d) Three dimensional defect
Answer: b
Explanation: Point defects are zero dimensional defects as they cannot extend in any direction in space. Point defects occur where an atom is missing or misplaced in a crystal lattice. The limit of the size of point defect is not defined.
2. Which of the following point defects can be attributed to from the below options?
i) Stress Fields
ii) Strain fields
iii) Charge
iv) Current
a) i) and ii)
b) ii) and iv)
c) i) and iii)
d) ii) and iv)
Answer: c
Explanation: Stress fields are produced due to point dislocation and charges are needed for point dislocation. When an atom dislocates from its original position to an interstitial position or it is completely removed from the lattice, hence creating stress fields.
3. Which is not a name given to vacancy in some ionic solid?
a) H-center
b) F-center
c) Color center
d) Luminescence center
Answer: a
Explanation: Other than H-center which is used when a halogen occupies the interstitial position, all the other terms are used for a vacancy in ionic solid. For some ionic solid when there is a vacancy in crystal, an F-center or color enter or luminescence center is formed due to which the ionic solid exhibits different colors.
4. What is the color of zinc oxide?
a) Blue
b) Red
c) Yellow
d) Orange
Answer: c
Explanation: In zinc oxide, there is a creation of F-centers, due to a vacancy in its lattice structure. As the F-centers absorbs light and shows complimentary color, zinc oxide exhibits yellow as its colour.
5. If the number of F-centers are more, the color of the compound gets more intense.
a) True
b) False
Answer: a
Explanation: When the number of F-center increases, more light is absorbed from the visible spectra and intense color is obtained. By the same logic when the number of F-centers are less, colors are less intense.
6. F-centers are _________
a) Cathodic vacancy in a crystal occupied by one or more paired electron
b) Cathodic vacancy in a crystal occupied by one or more unpaired electron
c) Anionic vacancy in a crystal occupied by one or more paired electron
d) Anionic vacancy in a crystal occupied by one or more unpaired electron
Answer: d
Explanation: F-centers occur when in a crystal the vacancies are filled by one or more unpaired electron. When there is an anionic vacancy the charge on the whole body becomes positive as an anion is negatively charged. The presence of the unpaired electron makes the body neutral and hence stable.
7. In which of the following defect the density of the crystal is affected?
a) Schottky defect
b) Frenkel defect
c) Stone-Wales defect
d) Antisite defect
Answer: a
Explanation: The density of the solid crystal in case of the Schottky defect is less than the theoretical density of the material. This happens as the total number of ions in the lattice is less than the theoretical number of ions according to its volume when this defect occurs.
8. Schottky and Frenkel defects are ___________
a) Interstitial and vacancy defects respectively
b) Vacancy and interstitial defect respectively
c) Both interstitial defects
d) Both vacancy defects
Answer: b
Explanation: Schottky defect occurs when oppositely charged ions leave the crystal and creating a vacancy and hence is a vacancy defect while in Frenkel defect an atom moves from its original site to an interstitial position and hence is an interstitial defect.
9. Which of the following compound shows both Schottky and frenkel defect?
a) Silver iodide
b) Silver bromide
c) Magnesium sulphide
d) Titanium oxide
Answer: b
Explanation: For a compound to show Schottky defect the size of anion and cation are similar size while Frenkel defect occurs where the size of the anion is larger than the cation. As the radius ratio of silver to bromine is intermediate, it shows both the defects.
10. For the given magnitude of shift which of the following can cause the formation of an off-center ion?
a) 0.1 Å
b) 0.05 Å
c) 0.5 Å
d) 1.1 Å
Answer: c
Explanation: Off center ions are a type of substitutional ion whose equilibrium position is a little shifted from its original lattice site. The magnitude of shift for an off center ion is typically in the range of 0.2Å to 1.0Å.
11. The presence of interstitial carbon atom increases the hardness of which of the following:
a) Martensite
b) Austenite
c) Cementite
d) Pearlite
Answer: a
Explanation: Martensite is formed in steel when the austenite form of iron is quenched. Due to rapid cooling, interstitial carbons are found in interstitial positions. The interstitial carbon is what makes martensite a hard form of steel.
12. How are point defects classified based on the source of the atom?
a) Statistical and structural
b) Random and ordered
c) Intrinsic and extrinsic
d) Interior and exterior
Answer: c
Explanation: When no foreign atom is present in the crystal lattice and the same kind of atoms are forming the defect then it is called as an intrinsic atom. When there is a presence of an additional atom in the crystal lattice, it is called extrinsic defect and hence they are classified according to the source of the atom.
13. In which of the following case the first element can occupy both lattice position and interstitial position?
a) Cu in FCC-Ni
b) C in FCC-Fe
c) B in steel
d) Al in FCC-Fe
Answer: c
Explanation: For the first element to occupy the lattice position the size of the first element should be like that of the second element while for the first element to occupy interstitial position the size of the first element should be less than the second element. Due to the intermediate size of boron crystal, it can occupy both lattice and interstitial position.
14. At temperatures greater than 570 degree centigrade, which of the following can be a stable composition of iron oxide?
a) Fe 0.99 O
b) Fe 0.9 O
c) Fe 0.96 O
d) Fe 0.97 O
Answer: b
Explanation: Over 570 degree centigrade, the composition of iron oxide is in the form of Fe O, where x lies between 0.05 to 0.16. Any value of x other than that will not form a stable composition of iron. We can see that only in Fe 0.9 O, x is 0.1 which lies between the permissible ranges.
This set of Materials Science Problems focuses on “Point Defects – 2”.
1. Which thermodynamic property increases in a crystalline solid due to the presence of vacancies?
a) Enthalpy
b) Entropy
c) Internal energy
d) Work done
Answer: b
Explanation: Presence of vacancies in crystalline solid creates randomness in structure due to which entropy increases as it is directly proportional to the number of vacancies per mole of solid.
2. Which type of diffusion occurs due to the exchange of an atom with vacancies?
a) Substitution diffusion
b) Elimination diffusion
c) Passive diffusion
d) Facilated diffusion
Answer: a
Explanation: Substitution as the name suggests it deal with substituting an atom or element in the empty gaps present in crystalline solid which are commonly called as a vacancy.
3. Which of the following technique is not used to measure the concentration of vacancy to determine the activation energy for its formation?
a) Positron annihilation technique
b) Thermal expansion measurements
c) Measuring resistivity after quenching
d) Thermal imaging
Answer: d
Explanation: Thermal imaging technique is used to determine the position of the defect. It gives the information about depth at which defect will be located. It does not give details about the concentration of vacancy.
4. Calculate temperature of copper at which equilibrium number of vacancies per cubic meter is 2.2*10 20 vacancies/m 3 . The energy of vacancy formation is 0.7ev/atom and total number of atom is 2*10 30 atom/m 3 .
a) 3541.4k
b) 300k
c) 354.14k
d) 2.82*10-3k
Answer: c
Explanation: The equilibrium number of vacancies Nv for a given quantity is given by
Nv = Nexp
T = -Qv/)
T = -0.7/(8.62*10 -5 *ln(2.2*10 20 /(2*10 30 )))
T = 354.14k.
5. Which of the following is not the feature of solute and solvent atoms that determine the degree to which former dissolve in latter?
a) Corrosion factor
b) Atomic size factor
c) Crystal structure
d) Valences
Answer: a
Explanation: Corrosion factor determines the rate at which a metal can be corroded it is not related to the solubility of solute and solvent.
6. How is the concentration of defect related with free energy?
a) The concentration of defect increases free energy
b) The concentration of defect decrease free energy
c) The concentration of defect is equal to free energy
d) The concentration of defect is not related to free energy
Answer: a
Explanation: Point defects are equilibrium defect varies inversely with free energy.
7. In which type of defect smaller cation can get displaced into an interstitial void?
a) Schottky defect
b) Intrinsic defect
c) Extrinsic defect
d) Frankel defect
Answer: d
Explanation: In some compounds where cation anion difference is large cation being smaller compared to anion tends to displace from its original position to the other position. This type of defect is called as Frankel defect.
8. Which of the following phenomenon creates point defect in ceramics?
a) Thermal excitation
b) Precipitation
c) Densification
d) Electrical conductivity
Answer: a
Explanation: In ceramics on providing external energy valence electrons get excited creating a point defect in ceramics. This phenomenon is known as the thermal excitation.
9. Which of the following oxides are highly defective?
a) Al 2 O 3
b) MgO
c) CaO
d) FeO
Answer: d
Explanation: FeO is a transition metal oxide. Now in this case FeO is cation deficient due to presence of at least 5% of iron in Fe 3+ state.
10. In case of point defect in polymers probability of which part of the polymer is likely to be defected more compared to other?
a) Center of polymer chain
b) Chain ends
c) Main chain units
d) Starting part of chain
Answer: b
Explanation: Chain ends being the outer most part of the polymeric chain the probability of formation of vacancies in this part is more hence they are more defected compared to other parts.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Linear Defects – 1”.
1. A dissolution in which an extra portion of a plane of atoms or a half plane terminates within a crystal is called as ________
a) Edge dislocation
b) Mixed dislocation
c) Interfacial dislocation
d) Screw dislocation
Answer: a
Explanation: Edge dislocations are the linear crystalline defects that are formed due to the extra half plane of atoms in the lattice.
2. The magnitude and direction of lattice distortion are expressed in terms of which vector?
a) Dislocation vector
b) Screw vector
c) Edge vector
d) Burger vector
Answer: d
Explanation: Burger vector is used to denote magnitude and direction. In physics, the Burgers vector, named after Dutch physicist Jan Burgers, is a vector, often denoted as b, that represents the magnitude and direction of the lattice distortion resulting from a dislocation in a crystal lattice.
3. What is the relative orientation of dislocation lines for edge dislocation?
a) Parallel
b) Perpendicular
c) Circular
d) Both parallel and perpendicular
Answer: b
Explanation: For edge dislocation the nature of dislocation line is perpendicular.
4. What type of direction will the burger vector of dislocation for a metallic material show?
a) Closed-packed crystallographic direction
b) Rounded-packed crystallographic direction
c) Open-packed crystallographic direction
d) Parallel-packed crystallographic direction
Answer: a
Explanation: For a metal being solid, its atoms are closely packed and also metals are crystalline in nature so the direction shown by the vector will be closed packed crystalline direction.
5. Which technique is used to observe dislocation?
a) Positron annihilation technique
b) Thermal imaging
c) Thermal expansion measurements
d) Electron-microscope technique
Answer: d
Explanation: This type of microscope consists of a high magnification transmission electron micrograph in which dark lines represent dislocation.
6. Path of screw dislocation is in the form of _______
a) Circular
b) Cylindrical
c) Spiral or helical
d) Rectangular
Answer: c
Explanation: Ramp that is traced around dislocation line is spiral or helical that’s the reason it is called screw dislocation.
7. Which type of deformation occurs due to dislocation?
a) Slip plastic deformation
b) Elastic deformation
c) It does not show deformation
d) Slip elastic deformation
Answer: a
Explanation: Dislocation involves sliding of crystal blocks over one another along the definite crystallographic plane which results in a slip.
8. Which type of stress is involved in the motion of screw dislocation?
a) Tensile stress
b) Shear stress
c) Compressive stress
d) Does not involve stress
Answer: b
Explanation: If shear stress is increased in screw dislocation it results in a slip of one layer over other which ultimately leads to deformation.
9. Which type of dislocation are included in mixed dislocation?
a) Only Edge dislocation
b) Only shear dislocation
c) Only screw dislocation
d) Both edge and screw dislocation
Answer: d
Explanation: Mixed dislocation is a combination of screw and edge dislocation. It does not consist of only pure edge or pure screw dislocation.
10. What is the mechanism in which edge dislocation move out of the slip is called _______
a) Climb dislocation
b) Screw dislocation
c) Shear dislocation
d) Slip dislocation
Answer: a
Explanation: In this type of dislocation edge moves perpendicular over its slip plane.
This set of Materials Science Question Paper focuses on “Linear Defects – 2”.
1. Which type of defect are line defects?
a) One-dimensional defect
b) Zero-dimensional defect
c) Two-dimensional defect
d) Three-dimensional defect
Answer: a
Explanation: Line defects are one dimensional defects as they extend in a singular direction in space. Line defects are present in solids whereas the whole row of atoms is arranged in anomalous order. Hence line defects are linear defects and one dimensional in nature.
2. Edge dislocation and skew dislocation are linear crystalline defects.
a) True
b) False
Answer: a
Explanation: Line defects are mainly dislocations which can be broadly classified into two distinct defects. These two dislocations are called edge dislocation and screw dislocation.
3. Which of the following statement is false?
a) Burger vector is the right angle to edge dislocation
b) In screw defect the line defect is parallel to the displacement vector
c) Grain boundary defect is a type of line defect
d) Line defect occurs during the recrystallization process or during slip
Answer: c
Explanation: Grain boundary defect is a two-dimensional defect. Grain boundary is the interface between two grains and hence they stop the dislocations from moving freely. Therefore, they cause a two-dimensional defect to spread around the grain boundary.
4. In which type of dislocation an extra plane is inserted inside the crystal?
a) Edge dislocation
b) Screw dislocation
c) Jog dislocation
d) Mixed dislocation
Answer: a
Explanation: The edge defect is simply pictured as an additional half plane of atoms in a lattice. The dislocations are termed a line defect because of the number of defective points created within the lattice along a line. Hence, an extra plane of atoms is added inside the crystal in this type of defect.
5. What is the difference between the angle of Burgers vector and dislocation line in edge dislocation and screw dislocation?
a) -90 degrees
b) 0 degrees
c) 45 degrees
d) 90 degrees
Answer: d
Explanation: The angle between Burgers vector and dislocation line in edge dislocation is 90 degrees while the angle between burger vector and dislocation line for screw dislocation is 0 degree. To find the difference we have subtract 0 from 90, giving us 90 degrees as our final answer.
6. To determine yield strength of a material which of the following needn’t be affected?
a) Solute hardening
b) Precipitation hardening
c) Work hardening
d) Martensic transformation
Answer: d
Explanation: Burgers vector plays an important role in determining yield strength by affecting solute hardening, precipitation hardening and work hardening. Martensic transformation which refers to quenching from high temperature doesn’t play any role in the determination of yield strength.
7. In which type of dislocation planes are displaced relative to each other through shear?
a) Edge dislocation
b) Screw dislocation
c) Jog dislocation
d) Mixed dislocation
Answer: b
Explanation: In screw dislocation, planes are displaced relative to each other through shear. The trace of the atomic planes around the screw dislocation makes spiral or whorled path sort of resembling a screw and hence, it is named screw dislocation.
8. In an edge dislocation, a helical path is traced around the dislocation line.
a) True
b) False
Answer: b
Explanation: A helical path is traced along the dislocation line in screw dislocation whereas in edge dislocation a new additional half plane of an atom is inserted and a screw like path is not traced by the dislocation.
9. Which of the following is fields are not present for edge dislocation?
a) Tensile
b) Compressive
c) Shear stress
d) Strain
Answer: d
Explanation: In the edge dislocation, tensile, compressive and shear stress field are present due to an additional half plane of atom added because of which stresses are produced but no strain is produced because of an edge dislocation.
10. Which of the following is fields are present for screw dislocation?
a) Tensile
b) Compressive
c) Shear stress
d) Strain
Answer: c
Explanation: As in screw dislocation a helical path is traced along a dislocation line, there is only presence of shear stress field and no compressive, tensile or strain field is produced. Shear stress field is produced due to the spiral aspect of this type of dislocation.
11. Which of the following dislocation can glide but not climb?
a) Screw dislocation
b) Edge dislocation
c) Jog dislocation
d) Mixed dislocation
Answer: a
Explanation: Screw dislocation can only glide in a crystal lattice along the helical path while edge dislocations can glide and climb as there is an extra plane of atom present.
12. What are the dislocation in which the line direction and Burgers vector are neither perpendicular nor parallel?
a) Screw dislocation
b) Edge dislocation
c) Jog dislocation
d) Mixed dislocation
Answer: d
Explanation: Mixed dislocation are dislocation consisting of both screw and edge dislocation character where in screw dislocation the line direction and burger vector are parallel and for edge dislocation it is perpendicular. Therefore, the angle between line direction and Burgers vector is neither perpendicular nor parallel.
13. Which of the following can be theoretical shear stress produced in metals?
a) 10 GPa
b) 32 GPa
c) 2 GPa
d) 50 GPa
Answer: a
Explanation: The theoretical shear stress is in the range of 3 Gpa to 30 GPa. 10GPa is the only option which lies within that range while 32 GPa, 2 GPa and 50 GPa are beyond the range in which the theoretical shear stress can lie for pure metal.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Interfacial Defects”.
1. Annealing twins which are found in metal have which type of crystal structure?
a) BCC
b) FCC
c) HCP
d) HCP and BCC
Answer: b
Explanation: Annealing twins are predominantly found in Face-Centered Cubic structure metals.
2. At room temperature what is an approximate order of vibration frequency in vibration per second?
a) 1013
b) 1010
c) 104
d) 107
Answer: a
Explanation: Since amplitude vibration is few thousands of nanometre at room temperature. The frequency of the periodic motion is known as a vibration frequency.
3. In polymeric material the surface of which type of layer is considered to be an interfacial defect?
a) Chain ends
b) Short side branches
c) Main chain unit
d) Chain folded layer
Answer: d
Explanation: Chain folded layers create/ are boundaries between two crystalline regions which results in the interfacial defect.
4. Which type of boundary exists in multiphase materials across which there is a sudden change in physical/chemical properties?
a) Phase boundary
b) Chain folded layer
c) Domain wall
d) Grain boundary
Answer: a
Explanation: Chain folded layers are boundaries in case of polymeric materials. Domain wall deals with ferromagnetic and ferromagnetic materials and multiphase deals with phase boundary.
5. What is the density of polycrystalline specimen virtually identical to?
a) Singe crystal of different material
b) Single crystal of same material
c) Different crystal of different material
d) Different crystal of same material
Answer: b
Explanation: Single crystal of same material will have the same crystalline structure so their density will be identical.
6. Which type of boundary causes a constant angle of tilt between lattice planes of the same type in adjacent regions of the sample?
a) Twinning boundary
b) Tilt boundary
c) Grain boundary
d) Domain wall
Answer: b
Explanation: When a small grain boundary is formed due to tilt in the angle of orientation is called tilt boundary. A Twin Boundary happens when the crystals on either side of a plane are mirror images of each other.
7. Volume defect or bulk defects are which dimension defect?
a) 1 dimension
b) 2 dimension
c) 3 dimension
d) 4 dimension
Answer: c
Explanation: Volume defects are three dimensional defects. Interfacial defects are two dimensional. In short volume defect is an application of interfacial defect.
8. Interfacial defect does not include which of the following defect?
a) Grain boundary
b) Twin boundary
c) Phase boundary
d) Volume defect
Answer: d
Explanation: Interfacial defects are 2 dimensional defects whereas volume defect is 3 dimensional defects. Grain boundary, Twin boundary and Phase boundary are types of interfacial defect.
9. What will be the interfacial energy for domain wall?
a) Greatest compared to other interfacial defects
b) Least compared to other interfacial defects
c) Less than external surface but more than other interfacial defects
d) Less than the external surface and grain boundary but more than other interfacial defects
Answer: b
Explanation: Domain wall is the boundary that separates the region having a different direction of magnetization in case of ferromagnetic and ferrimagnetic material. Hence interfacial energy is least in case of a domain. As magnetization energy is less compared to other energies.
10. Which dimension defect are interfacial defects?
a) 2 dimension
b) 1 dimension
c) 3 dimension
d) 4 dimension
Answer: a
Explanation: Interfacial defect are boundary defect that has 2 dimension and normally separate regions of the materials that have different crystal structures and/or crystallographic orientations. These imperfections include external surfaces, grain boundaries, twin boundaries, stacking faults, and phase boundaries.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Microscopic Examination”.
1. Calculate the average number of grains per square inch at a magnification of 100. Consider grain number is 40?
a) 5.49*10 9
b) 5.49*10 7
c) 5.49*10 11
d) 5.49*10 6
Answer: c
Explanation: Grain size number and average number of grains per square inch are related as,
N = 2 n-1
N = 2 40-1
N = 5.49*10 11 .
2. For grain size number which of the following is true?
a) Size of grains with grain size no 8 will be more than that of grain size no 5
b) Size of grains with grain size no 6 will be more than that of grain size no 7
c) Size of grains with grain size no 6 will be more than that of grain size no 2
d) Size of grains with grain size no 14 will be more than that of grain size no 15
Answer: b
Explanation: Grain size number ranges from 1 to 10. Larger the no of grain size smaller are the grains.
3. Which of the following is not an important application of microstructure examination?
a) To ensure that the associations between the properties and structure are properly understood
b) To predict the properties of materials once these relationships have been established
c) To design alloys with new property combinations
d) To ascertain the mode of chemical fracture
Answer: d
Explanation: First three are the applications of microstructure examination while in case of fourth, to ascertain mode of physical fracture is the application instead of chemical fracture.
4. Which of the following microscope are not used for microscopy?
a) Optical
b) Ultrasonic
c) Electron
d) Scanning probe
Answer: b
Explanation: Ultrasonic microscope has a very high resolution of the range of 300*300 pixels which is not desired for micro compounds. It is useful for compounds having very small size range.
5. Which technique is used to determine the grain size of polycrystalline materials?
a) Photo micrographic technique
b) Positron annihilation technique
c) Measuring resistivity after quenching
d) Thermal imaging
Answer: a
Explanation: Positron annihilation technique is used to measure resistivity after quenching, Thermal imaging this technique is used to measure the concentration of vacancy to determine the activation energy for its formation and Photo micrographic technique is used to determine the grain size of polycrystalline materials.
6. Which type of microscopic technique has been developed that generate topographical maps representing the surface features and characteristics of the specimen?
a) Optical
b) Ultrasonic
c) Electron
d) Scanning probe
Answer: d
Explanation: More recent scanning probe microscopic techniques have been developed that generate topographical maps representing the surface features and characteristics of the specimen. Examinations on the atomic and molecular levels are possible using these techniques.
7. Which of the following method is commonly used to determine grain size?
a) Precipitation
b) Standard comparison charts
c) Densification
d) Electrical conductivity
Answer: b
Explanation: Intercept and standard comparison charts are commonly used in grain size determination.
8. What is the range of grain size number in case of ASTM?
a) 1 to 10
b) 1 to 100
c) 1 to 1000
d) 1 to 10000
Answer: a
Explanation: Grain size number ranges from 1 to 10. Size of grain varies inversely with grain size number. Example if grain size number is 10 then the size of grain will be smallest and for 1 it will be largest.
9. What is the full form of ASTM?
a) American society for testing and materials
b) African society for testing and materials
c) American society for torque and momentum forces
d) American society for tensile motion forces
Answer: a
Explanation: The American Society for Testing and Materials has prepared several standard comparison charts, all having different average grain sizes.
10. Which of the following is not the structural characteristic of a polycrystalline specimen?
a) Shape
b) Average size
c) Reactivity
d) Diameter
Answer: c
Explanation: Shape, Average size and Diameter are the structural characteristics of polycrystalline specimen while reactivity is the chemical property.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Diffusion Mechanisms”.
1. Diffusion is the result of:
a) Random motion of particles
b) Concentration gradient
c) Kinetic energy of particles
d) All of the mentioned
Answer: d
Explanation: Particles in all three phases possess some kinetic energy and are constantly under random motion. However, the rate of this movement is proportional to the number of particles available and hence the net direction of diffusion is from higher concentration to lower.
2. Concentration gradient refers to:
a) Change of concentration with respect to time
b) Change of concentration with respect to space
c) Change of concentration with respect to temperature
d) None of the mentioned
Answer: b
Explanation: Net direction of diffusion depends on the concentration of particles in a particular region of space and hence concentration gradient is defined as the rate of change concentration of particles in a given sample with respect to time.
3. Interstitial diffusion is generally faster than diffusion by vacancy mode. This is because:
a) Number of interstitial sites is greater than vacancies
b) Vacancy diffusion requires more energy than interstitial diffusion
c) Interstitial species are smaller than substitution species
d) All of the mentioned
Answer: d
Explanation: At normal conditions probability of occurrence of an adjacent interstitial site is much greater than that of a vacancy. Moreover, the bondings between the host lattice and interstitial atoms are much weaker.
4. As the temperature rises, the rate of vacancy diffusion in metals:
a) increases
b) decreases
c) remains the same
d) may increase or decrease
Answer: a
Explanation: Since more energy is available at higher energy, it is easier to break existing bonds and form additional vacancies.
5. Generally, the metal-to-metal diffusion takes place by vacancy diffusion.
a) True
b) False
Answer: a
Explanation: Interstitial diffusion occurs for smaller impurities like Carbon, Oxygen, Hydrogen etc. For larger species vacancy diffusion is more common.
6. Osmosis is different from diffusion as:
a) Diffusion requires semi-permeable membrane
b) Osmosis requires a liquid solvent
c) Osmosis is a form of active transport
d) In osmosis, solute moves from lower concentration to higher
Answer: b
Explanation: Osmosis is a special type of diffusion where an SPM separates two liquid solutions. Solutes cannot pass through the SPM. As more solvent particles are present in dilute solution than the concentrated one, these particles move through SPM from the former to the latter.
7. Rate of solid-state diffusion does not depend on which of the following?
a) Temperature
b) Diffusing species
c) Host solid
d) Gravity
Answer: d
Explanation: Diffusion is the result of a random motion of particles, i.e. their kinetic energy rather than their potential energy. Hence gravity does not effect the rate.
8. Diffusion is not used in which of the following?
a) Doping of semiconductors
b) Manufacturing of alloys
c) Heat treatment of metals
d) Catalysis
Answer: b
Explanation: Alloy manufacturing is a bulk process, achieved by mixing metal melts. Whereas diffusion is a surface phenomenon.
9. Carburisation is a heat treatment used for case hardening steels. Carbon is trapped on steel surface by:
a) Osmosis
b) Interstitial diffusion
c) Vacancy diffusion
d) None of the mentioned
Answer: b
Explanation: Carbon forms interstitial carbides with iron due to the large difference in atomic radii.
10. You want to demonstrate the phenomenon of diffusion to a group of school kids using two coloured gases. For this, you need to slow down the process. Which of the following tricks will help you achieve this feat?
a) Cooling the gases
b) Using gases of large molecular weights
c) Decreasing the size of orifice
d) All of the mentioned
Answer: d
Explanation: Rate of diffusion is directly proportional to temperature and it is indirectly proportional to molecular weights.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Steady State Diffusion”.
1. In steady state diffusion which of the following remains constant?
a) Concentration gradient
b) Kinetic energy of particles
c) Potential energy of particles
d) Change of concentration with respect to temperature
Answer: a
Explanation: In steady state diffusion, the concentration of the diffusing with respect to space at any point remains constant. Kinetic energy and potential energy need not be constant.
2. Which of the following gases can be purified by allowing it to diffuse through palladium cap?
a) Oxygen
b) Hydrogen
c) Chlorine
d) Nitrogen
Answer: b
Explanation: When a gas at constant pressure pervades through a thin walled metal foil, steady state diffusion occurs. Hydrogen is purified by making it pass through a palladium cap after going through steady state diffusion.
3. Which of the following law is used for steady state diffusion?
a) Fick’s law
b) Newton’s law of diffusion
c) Bragg’s law
d) Charles’s law
Answer: a
Explanation: Fick’s law is used under steady state conditions to obtain the diffusion coefficient. Bragg’s law is used in diffraction of light while Charles’s law is used in thermodynamics and is also known as the law of volumes.
4. Which of the following is not a part of Fick’s first law?
a) Diffusion flux
b) Diffusion coefficient
c) Change in concentration with respect to the position in space
d) Change in concentration with respect to time
Answer: d
Explanation: Fick’s first law is given by: J = – D , where J is diffusion flux or diffusivity, D is diffusion coefficient and dc/dx stands for change in concentration with respect to the position in space. Hence change in concentration with respect to time is not a part of Flick’s first law.
5. Velocity of diffusing particles does not depend on _______
a) Temperature
b) Viscosity of the fluid
c) Size of the particles
d) Pressure
Answer: d
Explanation: Diffusion coefficient is proportional to square of velocity which depends on the temperature of the fluid, viscosity of the fluid and the size of particles. The velocity of particle does not depend on pressure.
6. Flux direction is opposite to the direction of the concentration gradient.
a) True
b) False
Answer: a
Explanation: Flux direction is opposite to the direction of the concentration gradient. Because of which there is a negative sign in Fick’s first law of diffusion on the right side of the equation.
7. The diffusivity of copper in copper increases by how many times when the temperature is increased from 500 ° C to 1000 °C?
a) 200000
b) 100000
c) 150000
d) 170000
Answer: a
Explanation: The diffusivity of copper in copper at 500 °C is 1e -18 while diffusivity at 1000 °C is 2e -13 . By dividing the values, we find that the diffusivity increases by 200000 times fold.
8. What is the shape of the graph for steady state diffusion where the concentration of diffusion species is in the y-axis and position is in x-axis?
a) Parabola
b) Hyperbola
c) Ellipse
d) Straight line
Answer: d
Explanation: The concentration of the diffusing species is directly proportional to position. Hence graph is a straight line with negative slope.
9. In dilute aqueous solutions which of the following can be the value of diffusion coefficient at room temperature?
a) 0.7e -9
b) 0.7e -10
c) 2.2e -9
d) 2.2e -10
Answer: a
Explanation: The diffusion coefficient in a dilute aqueous medium for most ions lies in the range of 0.6e -9 to 2e -9 m 2 /s. Only 0.7e -9 lies in the range while the others are beyond the range and hence it is the answer.
10. There is no difference between diffusion and net diffusion.
a) True
b) False
Answer: b
Explanation: In homogeneous mixture diffusion and net diffusion are same but in case of in homogeneous materials the effect of diffusion is seen to be changing in concentration with time and hence in this case the net diffusion and diffusion values are different.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Non-steady State Diffusion”.
1. Which of the following law is used to non-steady state diffusion?
a) Fick’s first law
b) Fick’s second law
c) Bragg’s law
d) Charles’s law
Answer: b
Explanation: Fick’s second law is used to obtain the diffusion coefficient. Bragg’s law is used in diffraction of light while Charles’s law is used in thermodynamics and is also known as the law of volumes.
2. Which of the following will diffuse the fastest in iron?
a) W
b) C
c) H
d) He
Answer: c
Explanation: Hydrogen due to its small size will diffuse the fastest in iron. Carbon also diffuses fast in iron which can be observed in carburizing of steel.
3. Which of the following law is a partial differential equation?
a) Fick’s first law
b) Fick’s second law
c) Bragg’s law
d) Charles’s law
Answer: b
Explanation: Fick’s second law is a partial differential law as it is defined as: On the right-hand side we have a partial differential of concentration with respect to time while on the left we have the product of diffusion constant and double partial differential of concentration with respect to the position in space.
4. Which of the following operator is used and on which side of Fick’s second law’s equation?
a) Laplacian operator, right hand side
b) Laplacian operator, left hand side
c) Curl operator, left hand side
d) Gradient, left hand side
Answer: a
Explanation: Laplacian operator whose symbol is Δ = ∇2, is used on the right side of the equation of Fick’s law. It replaces the double partial derivative of concentration with respect to space.
5. What is the dimension of d 2 c/dx 2 ?
a) cm 3
b) cm 5
c) cm -3
d) cm -5
Answer: d
Explanation: The numerator has the dimension of cm -3 and the denominator has a dimension of cm 2 . Therefore, the quantity has a dimension of cm -3 /cm 2 which gives us cm -5 as the dimension.
6. Concentration gradient varies with time for which of the following processes?
a) Non-steady state diffusion
b) Osmosis
c) Steady state diffusion
d) Filter
Answer: a
Explanation: The concentration gradient varies with time for non-steady state diffusion. Meanwhile, it remains constant for steady state diffusion.
7. In non-steady diffusion, a type of atom accumulates or depletes from a region.
a) True
b) False
Answer: a
Explanation: As the concentration gradient does not constant with respect to time. So the atoms get accumulated or depleted from certain regions from the system.
8. Gaussian error function in denoted as ef.
a) True
b) False
Answer: b
Explanation: Gaussian error function is denoted by the erf and its corresponding values can be found from standard mathematical tables. It is used to find the solution of Fick’s second law.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Influential Factors”.
1. On which of the following does diffusion not depend on?
a) Temperature
b) Pressure
c) Concentration difference
d) Diffusion distance
Answer: b
Explanation: Diffusion depends on the temperature, concentration difference as atoms diffuse from higher concentration region to lower concentration region, diffusion distance. It does not depend on pressure.
2. When something burns on the stove in the kitchen, the whole kitchen starts smelling smoky due to diffusion.
a) True
b) False
Answer: a
Explanation: When something burns on the stove, the atoms of the burnt food starts spreading in the kitchen by random atomic motion by the process of diffusion. The burnt food atoms start moving from places where their concentration is high to regions of low concentration.
3. If we increase the temperature, how is the diffusion rate affected?
a) Diffusion rate increases
b) Diffusion rate decreases
c) Diffusion rate decreases drastically
d) Diffusion rate is not affected
Answer: a
Explanation: As the temperature increases, the kinetic energy of particles increases and hence they start moving randomly faster. Due to the increase in energy the particles bounce again each other faster and start spreading evenly throughout the volume.
4. How is the diffusion rate affected by concentration difference?
a) Diffusion rate is not affected
b) Higher the concentration difference, higher the diffusion rate
c) Lower the concentration difference, higher the diffusion rate
d) Higher the concentration difference, lower the diffusion rate
Answer: b
Explanation: The particles tend to move from higher concentration region to lower concentration difference. Therefore, higher the concentration difference, higher is the rate of diffusion.
5. How is diffusion rate related to diffusion distance?
a) Directly related
b) Inversely related
c) Not related
d) Directly related to square of diffusion distance
Answer: b
Explanation: The diffusion rate is inversely proportional to the distance from which the particles are diffusing. Larger the diffusion distance, the rate of diffusion is slower and vice versa.
6. How is the rate of diffusion affected by the weight of diffusing atom?
a) Lighter atoms diffuse faster
b) Heavier atoms diffuse faster
c) Lighter atom diffuses slower
d) Rate of diffusion doesn’t depend on weight of diffusing atom
Answer: a
Explanation: At a given temperature, average energy of atoms is equal and hence the rate of diffusion will depend on the size and weight of the diffusing atom. A lighter atom will diffuse faster than a heavier atom.
7. Diffusion is slower for _________
a) Open crystal structure
b) Low density materials
c) Materials with lower melting temperature
d) Materials with covalent bonding
Answer: d
Explanation: Diffusion rate is high for open crystal structure, material with low density as there is a sample amount of free space to diffuse into and material with low melting temperature as the particles reach liquid state faster and hence diffusion rate increases. On the other hand, the rate of diffusion for materials with covalent bond is slower because they are stronger bonds.
8. Diffusion is slower in polycrystalline structure than single crystalline structure.
a) True
b) False
Answer: b
Explanation: The diffusion rate is faster in a polycrystalline structure than a single crystalline structure. This is because diffusion through grain boundaries is faster than volume diffusion.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Stress and Strain”.
1. Up to which point on the stress-strain curve is Hooke’s law valid?
a) Elastic limit
b) Yield point
c) Proportionality limit
d) Fracture point
Answer: c
Explanation: The proportionality limit is the point up till which the strain of an elastic body is proportional to the stress applied on it. While elastic point is the point up till which the elastic properties last. After fracture point the body breaks.
2. What is the unit for stress?
a) N/m 2
b) Nm 2
c) N/m
d) Nm
Answer: a
Explanation: Stress is basically forced upon the unit area. The dimension for force is N and the dimension of area is m 2 . Therefore, the unit for stress is the dimension of force divided by that of area which is N/mm 2 .
3. Strain is a dimensionless quantity.
a) True
b) False
Answer: a
Explanation: Strain is defined as the deformation produced on a body due to stress divided by a length of the body. Deformation due to longitudinal strength will have the same unit as that of length of the body therefore, strain is a dimensionless quantity.
4. Which of the following relation is stated by Hooke’s law?
a) Stress is directly proportional to strain
b) Stress is inversely proportional to strain
c) Stress is directly proportional to square of strain
d) Stress is inversely proportional to square of strain
Answer: a
Explanation: According to Hooke’s law, stress is directly proportional to strain and the ratio of stress to strain is denoted by Y or E and is called Young’s Modulus oof elasticity.
5. Given the shear modulus for aluminum as 2.4e +10 N/m 2 and the shear strain is given as 6e -5 . What is the value for shear stress?
a) 13.4e +5 N/m 2
b) 14.4e +5 N/m 2
c) 12.4e +5 N/m 2
d) 13.4e -5 N/m 2
Answer: b
Explanation: Shear modulus is the ratio of shear stress and shear strain. Therefore, if we simply multiply the shear modulus and shear strain we will obtain the shear stress. Hence the final answer is 2.4e +10 x 6e -5 which gives us 14.4e +5 N/m 2 as the final answer.
6. Which of the following can be the value of Poisson’s ratio for an engineering structure?
a) 2
b) 0.4
c) 29
d) 100
Answer: b
Explanation: The Poisson’s ratio for most of the engineering structure normally lies between 0.3 and 0.6. Therefore 2, 29, 100 cannot be valid values for Poisson’s ratio.
7. If the Poisson’s ratio is given as 0.3 and the Young’s modulus is given to 7e 10 . What will be the value for shear modulus?
a) 2.69e 10 N/m 2
b) 3.00e 10 N/m 2
c) 2.59e 10 N/m 2
d) 2.72e 10 N/m 2
Answer: a
Explanation: The relation between Young’s modulus, shear modulus and Poisson’s ratio are given by v = E/2G – 1. Taking the 1 on the left side and rearranging we get G = E/2. Inserting the values given in the question the answer comes out to be 2.69e 10 N/m 2 . Here E = Young’s modulus, G = shear modulus and v = Poisson’s ratio.
8. Stress strain curve for cemented tungsten carbide is:
a) Hyperbola
b) Parabola
c) A curve
d) Straight line
Answer: d
Explanation: The stress-strain curve for cemented tungsten carbide is a straight line as being a brittle material doesn’t have a plastic zone and therefore, it fractures after a certain load is applied.
9. Greater the angle of inclination of the stress strain curve less is the elasticity.
a) True
b) False
Answer: b
Explanation: IF the angle of inclination of a stress strain curve is high, the elastic zone of the material is more as the curve starts curving after the elastic limit. Hence the elasticity of the material is high.
10. Which of the following is found out by calculating the area under the stress strain graph?
a) Toughness
b) Hardness
c) Endurance
d) Strength
Answer: a
Explanation: Toughness is measured by calculating the area under the stress strain graph and is more for most ductile material than brittle material which has more toughness than ductile material.
This set of Advanced Materials Science Questions and Answers focuses on “Tension and Compression Tests”.
1. Which of the following property cannot be determined by a tensile test?
a) Yield strain
b) Yield stress
c) Elastic limit
d) Limit of proportionality
Answer: a
Explanation: Tensile tests is used to determine different kinds of mechanical properties like yield stress, elastic limit, maximum tensile strength, limit of proportionality.
2. Which type of load is applied in tensile testing?
a) Axial load
b) Shear load
c) Transverse load
d) Longitudinal load
Answer: a
Explanation: An axial load is applied to the material to be tested when performing tensile testing and the load is applied axially to the body to be tested.
3. Given the cross sectional are as 4 m 2 , what will be the gauge length?
a) 12.3 m
b) 13 m
c) 11.3 m
d) 12 m
Answer: c
Explanation: The formula for gauge length is Lo= 5.65* root over of Area of cross section. We know that under root 4 is 2, therefore 5.65*2 is equal to 11.3 m.
4. Which of the following does not affect the value of ultimate tensile strength?
a) Quality of surface finish
b) Speed of testing
c) Dimensional accuracy of the specimen
d) Length of the specimen
Answer: d
Explanation: The length of the specimen does not affect the value of ultimate tensile strength. While the quality of surface finish, speed of testing, dimensional accuracy of the specimen affect the value of ultimate tensile strength.
5. Which of the following is used to elongation in the material?
a) Clinometer
b) Extensiometer
c) Micrometer
d) Feeler gauge
Answer: b
Explanation: An extensiometer is a gauge which is attached to the specimen and it gives us the value of elongation in the body at a time. Feeler gauge and micrometer or clinometer cannot be used during the testing.
6. The yield limit of compression and the tensile test can be different for the same material.
a) True
b) False
Answer: a
Explanation: Titanium ( T i ) is a material which shows different amount of yielding when subjected to tensile testing compared to when it is subjected to compressive testing.
7. An UTM can be used to conduct both tensile and compressive testing.
a) True
b) False
Answer: a
Explanation: A universal testing machine can be used to conduct tests like tension, compression, shear, friction, tear, stiffness. Many other such mechanical properties can be tested.
8. Which of the following factors do not affect the testing?
a) Temperature
b) Increase in number of axes for application of load
c) Fatigue
d) Pressure
Answer: d
Explanation: Increase in temperature and increase in the number of axes for load application can affect the testing results in a tensile or compressive test.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Torsional Tests”.
1. Which of the following cannot be determined using a torsion test?
a) Modulus of elasticity in shear
b) Torsion yield strength
c) Modulus of rupture
d) Young’s modulus
Answer: d
Explanation: Modulus of elasticity in shear, torsion yield strength and modulus of rupture can all be determined by performing torsion test on material.
2. What is the use of weight head in a torsion testing equipment?
a) Holding the job only
b) Holding the job and applying twisting moment
c) Holding the job and measuring the twisting moment
d) It is not a part of torsion testing equipment
Answer: c
Explanation: The main job of weight head is to hold the job and measure the twisting moment.while twisting head holds the other end of job and applies twisting moment.
3. Which of the following is used to measure how much the specimen is twisted?
a) Micrometer
b) Clinometer
c) Troptometer
d) Tropometer
Answer: c
Explanation: Troptometer is an instrument which is used for measuring the angular distortion of the material. Mocrometer and vernier callipers are used to measure length. Tropometer measures amount of torsion for a bone.
4. Torsional stress multiplied with original cross sectional are is:
a) Maximum twisting load
b) Minimum twisting load
c) Minimum shear load
d) Yield shear load
Answer: a
Explanation: Torsional stress is given by the ratio of maximum twisting load and original are of cross section of the material. Therefore, torsional stress multiplied with original cross sectional gives us maximum twisting load.
5. Plastic deformation can only occur in case of torsional force.
a) True
b) False
Answer: b
Explanation: The above given statement is false as plastic deformation can occur in case of tensile, compressive and torsional load after a point. After this point, the body cannot recover its original shape.
6. What is the unit of polar moment of inertia?
a) m 2
b) m 5
c) m 3
d) m 4
Answer: d
Explanation: Polar moment of inertia denoted by J, is given by integration of radius square with respect to small area of cross-section. Hence the unit is 2 which is equal to m 4 .
7. Shear stress on a solid bar and hollow bar is same for given dimension.
a) True
b) False
Answer: b
Explanation: Shear stress for a hollow bar and a solid bar are different dimensions as the hollow bar has two dimensions, outer and inner radius because of which calculation is different than the solid bar which has only one diameter.
8. In which of the following the angle of twist increases fast for a small amount of torque?
a) Cold working condition
b) Hot working condition
c) Warm working condition
d) The increase is the same for cold working, hot working and warm working
Answer: b
Explanation: When the torsion test is conducted in hot working, it is observed that for a slight change in torque on the given specimen the angle of twist increase fast as the material becomes soft at hot working temperature.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Stress Transformation”.
1. How many shear stress components can act on a 3-D object?
a) 2
b) 4
c) 5
d) 6
Answer: d
Explanation: On a 3-dimensional body, total 9 stress components can act, out of which 3 are normal stress components while 6 of the other are tangential or shear stress component.
2. Which type of stress is plane stress?
a) One dimensional
b) Two dimensional
c) Zero dimensional
d) Three dimensional
Answer: b
Explanation: Plane stress is a two-dimensional stress in which stress components on any one direction is zero. For eg. All the stress components pertaining to z component is zero.
3. Principal plane is the plane in which ___________
a) Shear stress is maximum
b) Normal stress is zero
c) Shear stress is zero
d) It doesn’t depend upon stresses
Answer: c
Explanation: Principle planes are those planes where the value of shear stress is equal to zero and maximum or minimum value of normal stress is present at these points.
4. In a Mohr’s circle drawn on the x-y plane, which axis is the axis where normal stress is plotted?
a) X-axis
b) Y- axis
c) Z-axis
d) Normal stress isn’t related to Mohr’s circle
Answer: a
Explanation: In a Mohr’s circle, the x-axis or the horizontal axis in the x-y plane is the axis on which normal stress is plotted on. This axis is also called the abscissa.
5. In a Mohr’s circle drawn on the x-y plane, which axis is the axis where shear stress is plotted?
a) X-axis
b) Y- axis
c) Z-axis
d) Shear stress isn’t related to Mohr’s circle
Answer: b
Explanation: In a Mohr’s circle, the y-axis or the vertical axis in the x-y plane is the axis on which normal stress is plotted on. This axis is called the ordinate.
6. Which of following is not a graphical method for representing stress?
a) Lame’s stress ellipsoid
b) Cauchy’s stress quadric
c) Lame’s stress circle
d) Mohr’s circle
Answer: c
Explanation: Lame’s stress circle cannot be used for graphical representation of stresses while Lame’s stress ellipsoid, Mohr’s circle and Cauchy’s stress quadric are used for graphically representing stress.
7. Double angle method is a method to solve the problem in Lame’s stress ellipsoid.
a) True
b) False
Answer: b
Explanation: Double angle method cannot be used to solve Lame’s stress ellipsoid problems, it is used in case of Mohr’s circle. This method mainly has two rule you need to follow.
8. Principal stress is only the minimum stress.
a) True
b) False
Answer: b
Explanation: Principal stresses are maximum and minimum stresses which act on the body and planes on which they act are called the principal plane.
This set of Materials Science Questions and Answers for Aptitude test focuses on “Various Mechanical Properties”.
1. Up till which point will a body regain its original shape?
a) Yield point
b) Elastic limit
c) Fracture limit
d) Ultimate tensile strength point
Answer: b
Explanation: Elastic limit is a point up till which the body can regain its original shape even after deformation and change in shape. After this point the body cannot regain its original shape.
2. Plasticity increases with temperature.
a) True
b) False
Answer: a
Explanation: Plasticity increase with temperature. Metals have high plasticity at high temperature. Mainly manufacturing processes like forming, drawing, extrusion etc. are done after considering plasticity.
3. Which of the following is not an evidence of plastic action on the material?
a) Yield
b) Plastic flow
c) Fatigue
d) Creep
Answer: c
Explanation: When a body is acted upon by plastic actions, one of the following can be seen out of yield, plastic flow and creep. Fatigue isn’t an evidence left after plastic action on a body.
4. Which of the following is the property because of which a material can be drawn into wires?
a) Ductility
b) Elasticity
c) Malleability
d) Strength
Answer: a
Explanation: Ductility is the physical property by which the material can be drawn in wires. None of the other options matched this definition.
5. What is the unit of impact strength?
a) N/m
b) MN/m
c) MN/m 2
d) N/m 2
Answer: c
Explanation: The SI Unit for impact strength is expressed as MN/m 2 . The unit in the numerator is taken in mega newton as the force acting is very high in case of impact strength.
6. Arrange the following in increasing order of hardness: talc, gypsum, topaz diamond.
a) Talc, gypsum, topaz, diamond
b) Gypsum, topaz, talc, diamond
c) Diamond, topaz, talc, gypsum
d) Topaz, gypsum, talc, diamond
Answer: a
Explanation: Talc, gypsum, topaz and diamond is the correct order in which it is arranged in increasing order of hardness.
7. How is brittleness related to impact strength?
a) Brittleness is directly proportional to impact strength
b) Brittleness is inversely proportional to impact strength
c) Brittleness is directly proportional to a square of impact strength
d) Brittleness is inversely proportional to a square of impact strength
Answer: b
Explanation: Brittleness is inversely proportional to the value of impact strength of the body that is more the impact strength less is the brittleness and vice versa.
8. Which of the following properties is impact strength indicative of?
a) Elasticity
b) Hardness
c) Stiffness
d) Toughness
Answer: d
Explanation: Impact strength is indicative of toughness of material and is given by how much energy the material can absorb while going through plastic deformation.
9. Which of the following is not a correct designation of impact strength?
a) KCU
b) KCV
c) KCT
d) KCW
Answer: a
Explanation: The first two letter signify that it is impact strength and KC are used for that. The third letter signifies the type of notch used, for example, U notch signify that the notch is U shaped.
10. KCU is used more than the other KCT and KCV.
a) True
b) False
Answer: a
Explanation: This statement is true as KCU is more broadly used for impact strength while KCT and KCV are used in special cases.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Design and Safety Factors”.
1. Which of the following is the numerator of factor safety formula?
a) Working stress
b) Shear stress
c) Tensile stress
d) Ultimate stress
Answer: d
Explanation: Factor of safety is defined as ratio of ultimate stress and working stress. It is also called as factor of ignorance. The factor of safety is dependent on the type of load.
2. Which of the following can be the factor of safety for a dead load?
a) 6
b) 2
c) 4
d) 7
Answer: c
Explanation: For dead load, the range in which the factor of safety can lie is 4 to 5. Therefore only 4 lies in that range and 6, 2, 7 are all values which are beyond that range.
3. Which of the following can be the factor of safety for shock loading?
a) 11
b) 13
c) 4
d) 7
Answer: b
Explanation: For shock loading, the range in which the factor of safety can lie is 12 to 15. Therefore only 13 lies in that range and 11, 4, 7 are all values which are beyond that range.
4. Factor of safety is used to find out the reliability of the design.
a) True
b) False
Answer: a
Explanation: Factor of safety tells us about how much load the material can take before it fails. Basically, it states the load carrying capacity of a material beyond the actual load.
5. What can understand by the factor of safety equal to one?
a) It means that the structure will fail under load
b) It means that the structure will only support the actual load
c) it means that the structure will support more than the actual load
d) There is no relation between factor safety and load application
Answer: b
Explanation: When the factor of safety is one it means that the ultimate stress is equal to the working stress and therefore the body can only support load up to actual load and no more before failing.
6. For which of the following design factor of safety the design will work properly?
a) 0.1
b) 1
c) 2
d) 0.9
Answer: c
Explanation: If the design factor of safety is not more than 1 then the design may not work and will fail under certain conditions.
7. What is a safe factor of failure for a component which on failure can result in financial loss or serious injury?
a) 1
b) 2
c) 3
d) 4
Answer: d
Explanation: For components which on failing can be hazardous and can lead to serious injuries, death and financial loss, the factor of safety should be taken equal to or more than 4.
8. Design factor for most aircraft structures is 2.
a) True
b) False
Answer: b
Explanation: The design factor of safety for most aircraft structures or components is taken to be 1.5 and not 2. More factors affect this value, but it is most of the time taken as 1.5.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Concept of Dislocations”.
1. Edge dislocation and skew dislocation are linear crystalline defects.
a) True
b) False
Answer: a
Explanation: Line defects are mainly dislocations which can be broadly classified into two distinct defects. These two dislocations are called edge dislocation and screw dislocation.
2. In which type of dislocation an extra plane is inserted inside the crystal?
a) Edge dislocation
b) Screw dislocation
c) Jog dislocation
d) Mixed dislocation
Answer: a
Explanation: The edge defect is simply pictured as an additional half plane of atoms in a lattice. The dislocations are termed a line defect because of the number of defective points created within the lattice along a line. Hence, an extra plane of atoms is added inside the crystal in this type of defect.
3. What is the difference between the angle of Burgers vector and dislocation line in edge dislocation and screw dislocation?
a) -90 degrees
b) 0 degrees
c) 45 degrees
d) 90 degrees
Answer: d
Explanation: The angle between Burgers vector and dislocation line in edge dislocation is 90 degrees while the angle between burger vector and dislocation line for screw dislocation is 0 degree. To find the difference we have subtract 0 from 90, giving us 90 degrees as our final answer.
4. In which type of dislocation planes are displaced relative to each other through shear?
a) Edge dislocation
b) Screw dislocation
c) Jog dislocation
d) Mixed dislocation
Answer: b
Explanation: In screw dislocation, planes are displaced relative to each other through shear. The trace of the atomic planes around the screw dislocation makes spiral or whorled path sort of resembling a screw and hence, it is name screw dislocation.
5. In edge dislocation, a helical path is traced around the dislocation line.
a) True
b) False
Answer: b
Explanation: A helical path is traced along the dislocation line in screw dislocation whereas in edge dislocation a new additional half plane of atom is inserted and a screw like path is not traced by the dislocation.
6. Which of the following is fields are not present for edge dislocation?
a) Tensile
b) Compressive
c) Shear stress
d) Strain
Answer: d
Explanation: In an edge dislocation, tensile, compressive and shear stress field are present due to additional half plane of atom added because of which stresses are produced but no strain is produced because of the edge dislocation.
7. Which of the following is fields are present for screw dislocation?
a) Tensile
b) Compressive
c) Shear stress
d) Strain
Answer: c
Explanation: As in screw dislocation a helical path is traced along a dislocation line, there is only presence of shear stress field and no compressive, tensile or strain field is produced. Shear stress field is produced due to the spiral aspect of this type of dislocation.
8. Which of the following dislocation can glide but not climb?
a) Screw dislocation
b) Edge dislocation
c) Jog dislocation
d) Mixed dislocation
Answer: a
Explanation: Screw dislocation can only glide in a crystal lattice along the helical path while edge dislocations can glide and climb as there is an extra plane of atom present.
9. What is the dislocation in which the line direction and Burgers vector are neither perpendicular nor parallel?
a) Screw dislocation
b) Edge dislocation
c) Jog dislocation
d) Mixed dislocation
Answer: d
Explanation: Mixed dislocations are dislocation consisting of both screw and edge dislocation character where in screw dislocation the line direction and burger vector are parallel and for edge dislocation it is perpendicular. Therefore, the angle between line direction and Burgers vector is neither perpendicular nor parallel.
10. What can be the unit of dislocation density?
a) mm -2
b) mm -3
c) mm 2
d) mm
Answer: a
Explanation: Dislocation density is defined as the total dislocation length per unit volume and unit of length is mm and that of volume is mm 3 therefore, the unit of dislocation density will be mm -2 .
This set of Materials Science Multiple Choice Questions & Answers focuses on “Lattice Strain”.
1. Which of the following is not a lattice strain due to dislocation?
a) Tensile lattice strain
b) Compressive lattice strain
c) Shear lattice strain
d) Torsional lattice strain
Answer: d
Explanation: Due to the movement of dislocation in a material tensile lattice strain, compressive lattice strain and shear lattice strain are felt by the neighboring atoms in the lattice.
2. When atoms are deformed approximately what fraction of deformation energy is retained internally?
a) 5%
b) 10%
c) 15%
d) 20%
Answer: a
Explanation: When a metal is plastically deformed, the atoms inside the lattice retain approximately 5% of the deformation energy.
3. For which of the following dislocation the strain is pure shear?
a) Screw dislocation
b) Jog dislocation
c) Mixed dislocation
d) Edge dislocation
Answer: a
Explanation: In screw dislocation only, pure shear stress is felt by the body while in edge dislocation, jog dislocation and mixed dislocation, other types of lattice strains also exist.
4. Which of the following will decrease lattice strain?
a) Line defects
b) Point defects
c) Dislocation
d) Heating the material
Answer: d
Explanation: When a body is heated the strain on the body decreases whereas it increases when defects like line defects, point defects and dislocation are present in the lattice.
5. How high can dislocation density of a material be when it is heavily deformed?
a) 10 10 mm -2
b) 10 9 mm -2
c) 10 11 mm -2
d) 10 12 mm -2
Answer: a
Explanation: The dislocation density of a material increases with increase in deformation and the heavily deformed material will have dislocation density up to 10 10 mm -2 .
6. Two edge dislocation on same slip plane and the same sign will ________
a) Exert attractive force
b) Exert no force
c) Exert repulsive force
d) Exert shearing force
Answer: c
Explanation: When two dislocations are of the same sign and are located on the same slip plane they exert a repelling force on each other.
7. Dislocation annihilation occurs when two dislocations of different signs meet each other on the same plane.
a) True
b) False
Answer: a
Explanation: When two dislocations of opposite sign are on located on same slip plane the two dislocations exert an attractive force and then they will start moving towards each other on meeting dislocation annihilation takes place.
8. Shear strains are observed in the vicinity of the edge dislocation.
a) True
b) False
Answer: a
Explanation: Along with tensile and compressive strains, in edge dislocation shear strains are also observed in the neighboring regions of the dislocation.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Slip Systems”.
1. Slip plane along with the direction of slip is called a slip system.
a) True
b) False
Answer: a
Explanation: Slip system is a combination of a slip plane and the slip direction for which the dislocation moves easily and leads to plastic deformation. For each crystal structure there exists its own set of slip systems.
2. How many slip system are there in FCC lattice?
a) 12
b) 6
c) 10
d) 18
Answer: a
Explanation: The number of slip planes are four and the number of slip direction are three in an FCC lattice. Therefore the total number of slip system is given by their multiplication that is twelve.
3. Slip planes do not occur where ______
a) Atom density is high
b) Atom density is low
c) Atoms are closely placed
d) direction of slip plane is the same as the translation vector which is the shortest
Answer: b
Explanation: Slip planes occur in planes where the atom density is high and hence the atoms are closely packed. Further, the direction of slip plane is the same as that of the translation vector which is the shortest.
4. Which law is related to slip plane and slip direction?
a) Bragg’s law
b) Fick’s law
c) Schmid’s law
d) Such a law doesn’t exist
Answer: c
Explanation: Schmid’s law gives us a relation between critically resolved shear stress and stress applied on the material. Where critical resolved shear stress is that component of shear stress which is in the slip direction.
5. Which of the following factors are more accurate when used for polycrystal metals?
a) Schmid’s factor
b) Taylor factor
c) Independent factor
d) Max factor
Answer: b
Explanation: Schmid’s factor is accurate for FCC crystal but for polycrystal metals use of the Taylor factor gives us a more accurate result.
6. Value of critical resolved shear stress for a given material at a given temperature ______
a) Increases with time
b) Decreases with time
c) Decreases harshly with time
d) Remains constant
Answer: d
Explanation: The critical resolved shear stress is independent of time and for a given material at a given temperature its value remains constant. It varies with a change in temperature.
7. Which of the following stresses is required for the slip to occur?
a) Tensile stress
b) Compressive stress
c) Critical resolved shear stress
d) Slip doesn’t occur due to stress
Answer: c
Explanation: A critical resolved shear stress is that component of shear stress which is in the slip direction and hence needed for a slip to occur. Tensile or compressive stress aren’t needed for a slip.
8. How many slip systems are there in BCC lattice?
a) 36
b) 48
c) 24
d) 18
Answer: b
Explanation: The number of slip plane is 48 for a BCC material. There are 6 planes of type {110} with 2 direction which gives us 12, in addition, there are 24 systems of {123} and 12 systems of {112}. Hence we get a total of 48.
9. How many slip systems are there in hexagonal closed packed crystal?
a) 3
b) 6
c) 9
d) 18
Answer: a
Explanation: In a hexagonal closed packed structure the slip is limited in comparison to bcc or fcc and allows slip in dense basal planes where the number of slip planes are calculated to be 3.
10. Slip is important for deformation to occur.
a) True
b) False
Answer: a
Explanation: The above statement is true. Slip is the mechanism that is followed by the dislocation when under plastic force to undergo deformation which can be seen on a three-dimensional level due to these microscopic slips.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Strengthening Mechanisms”.
1. Which of the following isn’t a strengthening mechanism?
a) Grain size reduction
b) Solid solution strengthening
c) Strain hardening
d) Grain size increment
Answer: d
Explanation: Grain size reduction, solid solution strengthening and strain hardening are all strengthening mechanisms which increase the hardness of the material. Grain size increment isn’t a strengthening mechanism.
2. Which of the following isn’t a strengthening mechanism for multi-phase materials?
a) Precipitation strengthening
b) Dispersion strengthening
c) Solid solution strengthening
d) Martensite strengthening
Answer: c
Explanation: Precipitation strengthening, dispersion strengthening, martensite strengthening are strengthening mechanism used for multi-phase materials. Solid solution strengthening is used for single-phase materials.
3. The yield strength of a material going through grain size reduction increases by a factor, k multiplied by:
a) d 2
b) d 1/2
c) d -1/2
d) d -2
Answer: c
Explanation: Yield strength relation is given by Hall-Petch relation in which final yield strength is equal to initial yield strength plus k multiplied by d -1/2 .
4. Which of the following is not improved by grain size reduction?
a) Hardness
b) Toughness
c) Elasticity
d) strength
Answer: c
Explanation: Grain size reduction increases the hardness, toughness and the strength of the material. Elasticity is not increased by grain size reduction.
5. Which of the following is not a way of interaction between solute atoms and dislocation?
a) Elastic interaction
b) Plastic interaction
c) Modulus interaction
d) stacking fault interaction
Answer: b
Explanation: Plastic interaction isn’t a way of interaction of solute atom and dislocation while plastic interaction, modulus interaction and stacking fault interaction are ways of an interaction of solute atoms and dislocation.
6. Which of the following interactions will not continue to act at about 0.6Tm?
a) Elastic interaction
b) Modulus interaction
c) Electrical interaction
d) Long range interaction
Answer: c
Explanation: Elastic interaction, modulus interaction, long range interaction are all long range interactions which act at 0.6 Tm while short range interaction like electrical interaction doesn’t act at 0.6Tm.
7. Which is not a correct term for bands in yield point phenomenon?
a) Lüders bands
b) Hartmann lines
c) stretcher stains
d) Lüders lines
Answer: d
Explanation: Lüders lines isn’t a correct term for bands in yield point phenomenon. While Lüders bands, Hartmann lines, stretcher stains are a correct term which can be used for bands in yield point phenomenon.
8. At what angle are Hartmann lines inclined to the tensile axis?
a) 45 degrees
b) 15 degrees
c) 30 degrees
d) 20 degrees
Answer: a
Explanation: The Hartmann lines are inclined to an angle of 45 degrees approximately to the tensile axis.
9. In strain hardening, the body is plastically deformed.
a) True
b) False
Answer: a
Explanation: Strain hardening is a process which is done on a ductile method by deforming them plastically and increasing strain in the body and hence increasing the hardness.
10. In strain hardening, there is an increase in density.
a) True
b) False
Answer: b
Explanation: In strain hardening apart from changes in mechanical properties there are physical changes like decrease in density, a small increase in the thermal coefficient of expansion.
This set of Tricky Materials Science Questions and Answers focuses on “Recovery, Recrystallization and Grain Growth”.
1. In which of the following processes does recovery, recrystallization, grain growth take place?
a) Surface hardening
b) Tempering
c) Strengthening
d) Annealing
Answer: d
Explanation: In the process of annealing, the crystal goes through three stages which are called recovery, recrystallization and grain growth in order.
2. When a material is plastically deformed at low temperature relative to the melting temperature, which of the following change isn’t observed?
a) Change in grain shape
b) Strain hardening
c) Decrease in dislocation density
d) Increase in dislocation density
Answer: c
Explanation: When a body is plastically deformed at low temperatures compared to its melting point, we observe micro structural changes like change in grain growth, strain hardening and increase in dislocation density.
3. At which of the following temperature can recovery occur?
a) 0.2Tm
b) 0.4Tm
c) 0.5Tm
d) 0.6Tm
Answer: a
Explanation: Recovery occurs at a lower temperature than recrystallization or grain growth. Recovery takes place at the temperature below 0.3Tm.
4. Strain-relief crystallization takes place when deformed metals are heated.
a) True
b) False
Answer: a
Explanation: Recovery is subdivided into two parts, strain-relief crystallization and polygonization. Strain-relief crystallization occurs when deformed metals are heated and the latter takes place under certain conditions.
5. Which of the following statements are false in strain-relief crystallization?
a) Dislocation climb
b) Decrease in the electric resistance
c) Increase in density
d) Interaction of like signed dislocation
Answer: d
Explanation: When strain-relief crystallization takes place dislocation climb, an increase in density, and a decrease in electrical conductivity. During strain-relief crystallization interaction of unlike signed dislocation is observed.
6. By what percentage can the hardness decrease after strain-relief crystallization?
a) 12%
b) 5%
c) 8%
d) 17%
Answer: a
Explanation: After strain-relief crystallization, the hardness and the strength of the material decrease by 10-15% from their original value. On the other hand, ductility increases by that percentage.
7. In which of the following metal polygonization rarely takes place?
a) Copper
b) Iron
c) Aluminium
d) Molybdenum
Answer: a
Explanation: Polygonization is the process in which new grain boundaries are formed and isn’t common for all metals and observed after slight deformation. In copper and its alloy, this process rarely develops.
8. Which of the following processes can be used to refine the grain structure?
a) Recovery
b) Recrystallization
c) Grain growth
d) Such a process does not exist.
Answer: b
Explanation: In recrystallization new grains are formed with small nuclei and they grow until they cover the whole parent material. Therefore, the new grain structure is fine and hence the grain structure is refined.
9. Lowest temperature for recrystallization for iron is 270°C
a) True
b) False
Answer: b
Explanation: For commercially pure iron, the lowest temperature at which recrystallization can occur is equal to 450°C. For aluminium and copper, it is equal to 100°C and 270°C respectively.
10. Which of the following is false for grain growth?
a) The grains start growing
b) Grain growth accelerates with increase in temperature
c) Decrease in free energy
d) Increase of surface energy
Answer: d
Explanation: The surface energy decreases during grain growth because of which free energy decreases. The grain starts growing and grain growth accelerates with increase in temperature.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Fundamentals of Failure”.
1. Improper heat treatment can cause mechanical failure.
a) True
b) False
Answer: a
Explanation: There are many causes of mechanical failure such as improper heat treatment, misuse, design errors, improper material and many other causes.
2. Buckling in a column occurs in the material due to which of the following forces?
a) Compressive
b) Tensile
c) Shear
d) It doesn’t occur due to a force
Answer: a
Explanation: Buckling in columns is a type of mechanical failure which occurs in materials due to the application of compressive load.
3. Which of the following is not a factor affecting fracture?
a) Stress concentration
b) Temperature
c) Pressure
d) Speed of loading
Answer: c
Explanation: Pressure isn’t a factor which affects fracture. Fracture of a material id affected by factors like stress concentration, thermal shock, temperature and speed of loading.
4. Which of the following is false?
a) Notch is a sudden change in section of a material
b) Stress concentration is produced due to notches
c) Notches change the stress applied to the body
d) Smaller the tip of the notch, less the increase in stress
Answer: d
Explanation: A notch is a sudden change in section of a material and stress concentrations are produced due to it. The smaller the tip of a notch the larger is the increase in stress.
5. Is the speed of loading is increased then:
a) Chances of fracture increases
b) Chances of fracture decreases
c) Chances of fracture remain the same
d) Elasticity of the body increases
Answer: a
Explanation: When the speed of loading is increased, the stress increases suddenly on the same section of the material which can lead to early failure in the form of fracture.
6. At what temperature is steel ductile?
a) -10 °C
b) -5 °C
c) -3 °C
d) 4 °C
Answer: d
Explanation: Steel acts as a ductile material at a temperature above 0 °C while it acts as a brittle material below 0 °C. Therefore at -10 °C, -5 °C, -3 °C steel will be brittle and not ductile.
7. Which of the following decreases transition temperature in steel?
a) Carbon
b) Nitrogen
c) Phosphorous
d) Manganese
Answer: d
Explanation: Alloying elements like manganese and nickel decrease the transition temperature of steel while alloying elements like carbon, nitrogen and phosphorous increases the transition temperature.
8. When hot water is poured into the cold glass, the glass may crack.
a) True
b) False
Answer: a
Explanation: The above statement is true. When hot water is poured in a cold glass, the glass may get cracked due to thermal shock due to the sudden change in temperature of the glass.
9. What is the relation between fracture toughness and thickness?
a) Fracture toughness decreases with increase in thickness
b) Fracture toughness increases with increase in thickness
c) Fracture toughness does not depend on the thickness
d) Fracture toughness increase linearly with an increase in thickness
Answer: a
Explanation: As the thickness increases the fracture toughness of the material decreases. It follows a curve and is not a linear graph.
10. Which of the following elements reduce fracture toughness in steel?
a) Phosphorous
b) Manganese
c) Iron
d) Aluminium
Answer: a
Explanation: There are some alloying elements which reduce fracture toughness in alloys. For an alloy like steel, phosphorous and sulphur decrease the fracture toughness in steel.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Ductile Fracture”.
1. Necking occurs in which of the following fractures?
a) Ductile fractures
b) Brittle fracture
c) Fatigue
d) It doesn’t occur during fracture
Answer: a
Explanation: Necking occurs when tensile force is applied on metals and it occurs when ductile failure is occurring. In brittle fracture the material just breaks before breaking.
2. In ductile fracture, at what angle to the tensile axis does the crack propagate outwardly to the surface of the material?
a) 90°
b) 30°
c) 45°
d) 15°
Answer: c
Explanation: The crack propagates outwardly to the surface of the material at an angle of 45° to the tensile axis and this type of fracture is called “cup and cone fracture”.
3. At the point of necking which of the following is false?
a) Strain hardening occurs at this point
b) Cross sectional area increases
c) Cross sectional area decreases
d) Strength increases
Answer: b
Explanation: At the point of the necking the strength increases due to strain hardening and the cross-sectional areas decreases at the same time. At the time where cross sectional area decreases faster than necking starts.
4. Ductile fracture happens after extensive plastic deformations.
a) True
b) False
Answer: a
Explanation: Unlike brittle fracture, ductile fracture happens after extensive plastic deformation and goes through multiple visible stages before the final fracture is observed.
5. Which of the following cannot be a reason for ductile failure?
a) Error in design
b) Improper material
c) Improper manufacturing techniques
d) Unforeseen operating condition
Answer: d
Explanation: Ductile fracture is a slow process with many steps and under unforeseen operating conditions if the fracture is going to occur it will be noticeable and can be avoidable.
6. After which point is necking observed?
a) Ultimate strength
b) Yield strength
c) Elastic point
d) Fracture point
Answer: a
Explanation: Necking in a ductile material is observed after the body crosses the point of ultimate strength on the stress-strain curve.
7. What is the amount of strain in a stable neck is called?
a) Natural draw ratio
b) Forced draw ratio
c) Poisson’s ratio
d) Physical activity ratio
Answer: a
Explanation: Natural draw ratio is the name given to the amount of strain in a stable neck during necking of a material under load.
8. Material subjected to only tensile force even during necking.
a) True
b) False
Answer: b
Explanation: Material during necking due to high dislocation density is subjected to a complex stress. At this point, the material isn’t subjected only a single tensile force.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Brittle Fracture”.
1. Which of the following is associated with minimum plastic deformation?
a) Ductile fracture
b) Brittle fracture
c) Fatigue
d) It doesn’t occur during fracture
Answer: b
Explanation: In brittle fracture, the plastic deformation occurring in the body is minimum and there is a rapid movement of crack with a very little amount of plastic deformation.
2. Which of the following fracture mechanisms in which the crack propagates more rapidly?
a) Ductile fracture
b) Brittle fracture
c) Fatigue
d) It doesn’t occur during fracture
Answer: b
Explanation: In brittle fracture, after a little plastic deformation the material fractures and then the crack propagates rapidly, making the material break.
3. Below which point does brittle fracture occur?
a) Ultimate tensile strength
b) Fracture point
c) Elastic limit
d) Yield point
Answer: d
Explanation: Fatigue is one of the mechanical failures of the metals that occur due to cyclic loading. It occurs when the stress applied is less than the yield stress or yield point.
4. Cleavage planes are a term associated with ductile fracture.
a) True
b) False
Answer: b
Explanation: Brittle fracture occurs generally along crystal planes called cleavage planes where the number of atomic bonds are relatively low.
5. The tendency of brittle fracture increases with:
a) Decreasing temperature
b) Increasing temperature
c) Decrease in strain rate
d) It doesn’t depend on temperature or strain rate
Answer: a
Explanation: The tendency of brittle fracture to be observed increases as the temperature decreases.
6. The tendency of brittle fracture increases with:
a) Increasing temperature
b) Increase in strain rate
c) Decrease in strain rate
d) It doesn’t depend on temperature or strain rate
Answer: b
Explanation: The tendency of brittle fracture to be observed increases as the strain rate of the body increases. As the strain rate increases the body dislocations start piling up and ultimately leading to failure.
7. Which of the following statement is true regarding the toughness of a metal?
a) Energy consumed is less in ductile fracture than brittle fracture
b) Energy consumed is more in ductile fracture than brittle fracture
c) Energy consumed in the brittle fracture is same as the ductile fracture
d) Energy consumed is more in brittle fracture than ductile fracture
Answer: b
Explanation: As brittle fracture less plastic deformation and absorbs less amount of energy before breaking, the energy consumed by brittle fracture is less than the ductile fracture.
8. Which of the theory is related to brittle fracture?
a) Laundau theory
b) Dirac hole theory
c) Valence bond theory
d) Griffith’s theory
Answer: d
Explanation: Griffith’s theory is a theory which was postulated by Griffith and is related to brittle fracture. It is known as Griffith’s theory of brittle fracture.
9. The graph for Griffith’s crack is ____________
a) An ellipse
b) A circle
c) A straight line
d) A hyperbola
Answer: a
Explanation: The graph for Griffith’s crack is an ellipse. The graph tensile stress applied perpendicular to the length of crack and the length of the crack.
10. Surface energy of the specimen increases when the crack lengthens.
a) True
b) False
Answer: a
Explanation: When the crack lengthens the surface area increases and hence the surface energy of the specimen increases.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Fracture Mechanics”.
1. Which of the following part of mechanics deals with study of crack propagation?
a) Solid mechanics
b) Fluid mechanics
c) Applied mechanics
d) Fracture mechanics
Answer: d
Explanation: Fracture mechanics is that part of mechanics which deals with the study of propagation of cracks. Solid mechanics and fluid mechanics deal with solid body and fluid respectively.
2. Which of the following is not a mode of application of force for crack propagation?
a) Opening mode
b) Sliding mode
c) Tearing mode
d) Rolling mode
Answer: d
Explanation: The application of force for the crack to propagate can be mainly of three types which are opening mode, tearing mode, sliding mode. Rolling mode cannot be used.
3. Fractography is the study of surfaces of materials which are fractured
a) True
b) False
Answer: a
Explanation: The above statement is true and fractography is indeed the study of surfaces of materials which are fractured. They are used mainly in forensic engineering or during failure analysis.
4. What amount of actual stress would be needed to fracture bulk glass?
a) 10 MPa
b) 20 MPa
c) 100 MPa
d) 50 MPa
Answer: c
Explanation: To fracture bulk glass, a force of about 100 Mpa or 15000 psi would be needed.
5. What amount of actual stress would be needed to fracture bulk glass?
a) 1000 MPa
b) 2000 MPa
c) 10000 MPa
d) 5000 MPa
Answer: c
Explanation: To fracture bulk glass, theoretically the stress needed to break the atomic bonds of the glass would be 10000 Mpa or 1500000 psi.
6. According to Griffith if f is stress at fracture and a is flaw length then which of the following is true?
a) f*a 1/2
b) f*a
c) f/a
d) f/a 1/2
Answer: a
Explanation: Griffith on conducting his experiment found out that the multiplication of stress at fracture and the square root of the flaw length remains constant.
7. Which of the following scientist proposed a modification to Griffith’s theory?
a) G. R. Irwin
b) Albert Einstein
c) Isaac Newton
d) There was no modification proposed.
Answer: a
Explanation: G. R. Irwin and people working under him at the U.S. Naval Research Laboratory found out that plasticity also plays a role in fracture of material and hence they proposed a modification.
8. What is the unit of G from Griffith’s energy criterion?
a) J-m 2
b) J-m
c) J/m 2
d) J/m
Answer: c
Explanation: G is the surface energy and is the given by energy per unit area which can be found out by dividing J by m 2 to get the final answer as J/m 2 .
9. For polymers close to glass transition temperature which of the following can be a value of G?
a) 1 J/m 2
b) 900 J/m 2
c) 1200 J/m 2
d) 1400 J/m 2
Answer: b
Explanation: 900 J/m 2 can be value of G for polymers close to glass transition temperature as the range of the G for this case is known to be 2 J/m 2 to 1000 J/m 2 . As the other options lie out of this range, there is only one correct answer.
10. Fracture stress decreases as fiber diameter decreases.
a) True
b) False
Answer: b
Explanation: The above statement is false as the fracture strength is known to increase when the fiber diameter decreases as observed by Griffith.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Impact Fracture Tests”.
1. What is the unit of impact strength?
a) N/m
b) MN/m
c) MN/m 2
d) N/m 2
Answer: c
Explanation: The SI Unit for impact strength is expressed as MN/m 2 . The unit in numerator is taken in mega newton as the force acting is very high in case of impact strength.
2. Which of the following properties is impact strength indicative of?
a) Elasticity
b) Hardness
c) Stiffness
d) Toughness
Answer: d
Explanation: Impact strength is indicative of toughness of material and is given by how much energy the material can absorb while going through plastic deformation.
3. Which of the following is false?
a) Notch is a sudden change in section of a material
b) Stress concentration is produced due to notches
c) Notches change the stress applied to the body
d) Smaller the tip of the notch, less the increase in stress
Answer: d
Explanation: A notch is a sudden change in section of a material and stress concentrations are produced due to it. The smaller the tip of a notch the larger is the increase in stress.
4. Which of the following is not notch sensitive?
a) Carbon
b) Steel
c) Plastic
d) FCC metal
Answer: d
Explanation: Tendency of a material to behave as a brittle material in presence of a notch is termed as notch sensitivity. Carbons, steels and plastics which are notch sensitive while FCC metals aren’t notch senitive.
5. Charpy test is not a type of impact test.
a) True
b) False
Answer: b
Explanation: Charpy and Izod test are the two standard testing methods in case of impact fracture tests.
6. What is the angle of a standard notch?
a) 10°
b) 20°
c) 45°
d) 30°
Answer: c
Explanation: As standard notch which is made on the material during impact fracture testing has an angle of 45°. The type of notch used in case of Charpy and Izod test is V-notch.
7. What is the dimension of material used in case of Izod test?
a) 10 mm * 10 mm * 75 mm
b) 10 mm * 10 mm * 65 mm
c) 5 mm * 5 mm * 75 mm
d) 5 mm * 5 mm * 65 mm
Answer: a
Explanation: In Izod test the specimen is taken of the dimension 10 mm * 10 mm * 75 mm where the width and breadth of the material are 10 mm and 10 mm respectively while the length is 75 mm.
8. What is the dimension of material used in case of Charpy test?
a) 10 mm * 10 mm * 55 mm
b) 10 mm * 10 mm * 65 mm
c) 5 mm * 5 mm * 55 mm
d) 5 mm * 5 mm * 65 mm
Answer: a
Explanation: In Charpy test the specimen is taken of the dimension 10 mm * 10 mm * 55 mm where the width and breadth of the material are 10 mm and 10 mm respectively while the length is 55 mm.
9. The direction of a blow of hammer is opposite to the notch section in case of Izod test.
a) True
b) False
Answer: b
Explanation: The above statement is false as the direction of the blow of hammer is opposite to the notch section in case of Charpy test and the direction are same in case of the Izod test.
10. Which of the following is the Charpy V impact strength for annealed pure copper?
a) 30 J
b) 31 J
c) 32 J
d) 34 J
Answer: d
Explanation: The value of Charpy V impact strength of annealed pure copper is experimentally found out to be 34 J.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Fatigue”.
1. Which of the following is failure of material due to cyclic stress?
a) Brittle fracture
b) Ductile fracture
c) Creep
d) Fatigue
Answer: d
Explanation: Fatigue is the type of failure which is observed in that material which is subjected to cyclic stress cycles. It can also be defined as the number of stress cycle a material can withstand before failing.
2. What can be height of an extrusion or an intrusion which is responsible for crack initiation in case of fatigue 2*10 -6
b) 2*10 -8
c) 10 -5
d) 10 -8
Answer: a
Explanation: In case of fatigue, there is movement of dislocation because of which local deformation called extrusions are form in slip bands which are accompanied by intrusions. These extrusion and intrusion have a height ranging from 10 -6 cm to 10 -7 cm.
3. Which of the following is the most common type of failure in industry?
a) Brittle fracture
b) Ductile fracture
c) Creep
d) Fatigue
Answer: d
Explanation: Almost 80% of the failure in the engineering industry occur due to fatigue failure. As components are used for a long time, the material is subjected to stress cycles and will fail due to fatigue.
4. Below which point does fatigue occur?
a) Ultimate strength
b) Fracture point
c) Elastic limit
d) Yield point
Answer: d
Explanation: Fatigue is one of the mechanical failures of the metals that occur due to cyclic loading. It occurs when the stress applied is less than the yield stress or yield point.
5. Which of the following is not a zone of fatigue fracture?
a) Zone of crack nucleation
b) Fatigue zone
c) Elastic zone
d) Final fracture
Answer: c
Explanation: The elastic zone isn’t a zone of fatigue fracture. The main three zones in order of their occurrence in fatigue fracture are zone of crack nucleation, fatigue zone. Final fracture.
6. Corrosion can increase fatigue life.
a) True
b) False
Answer: b
Explanation: The above statement is false. The fatigue life decreases if corrosion, erosion or other chemical attacks are not prevented during processing of the material or during heat treatment.
7. What is the speed of the motor in rotating beam fatigue test?
a) 200 rpm
b) 500 rpm
c) 1000 rpm
d) 1500 rpm
Answer: c
Explanation: In rotating beam fatigue test, the test machine is high speed with the motor running at 1000 rpm. With the help of the motor, the bending moment is applied on the material.
8. The S-N curve for mild steel never becomes a horizontal line.
a) True
b) False
Answer: b
Explanation: The above statement is false. The S-N curve which the curve between stress and number of cycles on the y and x axis respectively becomes a straight line for steel and titanium.
9. In Wohler’s Fatigue test, how many cycles can cast iron to be subjected to before failure?
a) 10,000,000
b) 100,000,000
c) 5,000,000
d) 1,000,000
Answer: a
Explanation: Cast iron or cast steel in Wohler’s Fatigue test can approximately be subjected to 10,000,000 cycles before it fails.
10. Which of the following is not a theory of fatigue?
a) Orowan theory
b) Griffith’s theory
c) Fatigue limit theory
d) Wood’s theory
Answer: b
Explanation: Griffith’s theory is a theory related to fracture mechanics and it isn’t a theory of fatigue. Orowan theory, fatigue limit theory and wood’s theory are the three main theory of fatigue.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Creep”.
1. Which of the following is a slow rise of plastic deformation under the action of shear stresses when it is below the yield strength of the material?
a) Brittle fracture
b) Ductile fracture
c) Creep
d) Fatigue
Answer: c
Explanation: Creep is defined as a slow rise of plastic deformation under the action of shear stresses when it is below the yield strength of the material.
2. Which of the following isn’t a stage of creep?
a) Transient creep stage
b) Constant creep stage
c) Fracture stage
d) Steady stage creep stage
Answer: b
Explanation: Transient creep stage, steady stage creep stage and fracture stage are the three stages of creep called as primary, secondary and tertiary creep respectively.
3. Which of the following stage is also known as the unstable stage?
a) Transient creep stage
b) Constant creep stage
c) Fracture stage
d) Steady stage creep stage
Answer: a
Explanation: Transient stage or primary creep is also called the unstable stage and in this stage, there is a gradual decrease in deformation rate to a definite constant value.
4. In which of the stages, do we observe a constant deformation rate?
a) Transient creep stage
b) Constant creep stage
c) Fracture stage
d) Steady stage creep stage
Answer: d
Explanation: Steady stage creep stage or secondary creep is the stage which is characterized by a constant deformation rate.
5. In which of the following stages do the deformation rate increases and causes failure?
a) Transient creep stage
b) Constant creep stage
c) Fracture stage
d) Steady stage creep stage
Answer: c
Explanation: Fracture stage or the tertiary creep is that stage where the material deformation rate increases and finally results in failure of that material.
6. Creep depends on temperature.
a) True
b) False
Answer: a
Explanation: The above statement is true. Creep is dependent on temperature and stress. Increase in temperature for a constant stress can decrease the time of the second stage and hence accelerate failure.
7. Above what temperature is the phenomenon of creep important in steel?
a) 200 °C
b) 500 °C
c) 300 °C
d) 600 °C
Answer: c
Explanation: For steel, the phenomenon of creep is important at a temperature above 300 °C while in polymer it is significant at room temperature.
8. Which of the following is true?
a) The slope of the strain-time graph increases with temperature and stress
b) The slope of strain-time graph decreases with temperature
c) The slope of strain-time graph decreases with stress
d) The slope of strain-time graph does not depend on temperature or stress
Answer: a
Explanation: The slope of a strain-time graph increases with the increase in temperature. The slope of a strain-time graph increases with the increase in stress too.
9. What is the nature of the curve of a viscous creep?
a) Parabola
b) Hyperbola
c) Straight line passing through an origin
d) Circle
Answer: c
Explanation: The nature of the curve for a viscous creep is a straight line passing through the origin while it is a horizontal line for sudden creep.
10. Diffusion creep is a type of creep. The slope of a strain-time graph increases with the increase in temperature.
a) True
b) False
Answer: a
Explanation: Diffusion creep, logarithmic creep and recovery creep are the three major types of creep. This classification is according to the temperature at which the creep occurs. Diffusion creep occurs at a temperature above 0.7 Tm.
This set of Materials Science Multiple Choice Questions & Answers focuses on “High Temperature Alloys”.
1. Which of the following is not an alloy?
a) Duralumin
b) Bismuth
c) Magnalium
d) Alnico
Answer: b
Explanation: Bismuth is a metal with symbol Bi and atomic number 83. Duralimn is an alloy of copper, magnalium is an alloy of magnesium and Alnico is an alloy of aluminium, copper and cobalt.
2. Which of the following is a high temperature alloy resistant to?
a) Tensile compression
b) Tensile elongation
c) Creep
d) Fatigue
Answer: c
Explanation: Alloys resistant to creep have high melting temperature and therefore are high temperature alloys.
3. Alloys resistant to creep have a high modulus of elasticity.
a) True
b) False
Answer: a
Explanation: The above statement is true. An alloy which is resistant to creep have a high modulus of elasticity and have high melting point thus giving then the name high temperature alloys.
4. Which of the relationship holds?
a) Higher the melting temperature greater is the elastic modulus
b) Lower the melting temperature greater is the elastic modulus
c) Higher the melting temperature smaller is the elastic modulus
d) There is no relationship between the melting temperature and elastic modulus
Answer: a
Explanation: The melting temperature of an alloy and its modulus of elasticity hold a direct relationship. Therefore, higher the melting temperature greater is the elastic modulus.
5. Which of the following doesn’t have high resistance to creep?
a) Stainless steel
b) Refractory metals
c) Superalloys
d) Magnesium
Answer: d
Explanation: Stainless steel, refractory metals and super alloys have resistance to creep and hence are used for high temperature usage. Magnesium doesn’t have a high resistance to creep.
6. Which of the following does not enhance the creep resistance of an alloy?
a) Solid-solution alloying
b) Addition of a dispersed phase
c) directional solidification
d) Heat treatment
Answer: d
Explanation: Heat treatment does not enhance the creep resistance of an alloy. Solid-solution alloying and addition of dispersed phase are used for that outcome. Other advanced techniques like directional solidification can also be employed.
7. Which of the following is created by directional solidification?
a) Single crystal components
b) Polycrystalline components
c) Short grains
d) Elongated grains
Answer: a
Explanation: In directional solidification, highly elongated grains or single-crystal components are formed.
8. Controlled unidirectional solidification of an alloy is a technique to increase creep resistance.
a) True
b) False
Answer: a
Explanation: The above statement is true. Controlled unidirectional solidification of alloys is a technique used to increase the creep resistance of an alloy.
This set of Materials Science Quiz focuses on “Basic Concepts of Phase Diagrams”.
1. Which of the following is/are the components of a brass alloy?
a) Brass, Copper, Zinc
b) Copper only
c) Zinc only
d) Both Copper and Zinc
Answer: d
Explanation: Components are pure metals and/or compounds of which an alloy is composed. Brass is an alloy and Copper and zinc are components.
2. At certain temperature the maximum concentration of solute atoms that dissolve in solvent to form solid solution, this condition is called __________
a) Solubility
b) Formation of phase
c) Solubility limit
d) Formation of super saturated solution
Answer: c
Explanation: At this limit there will maximum solubility o solution and solution formed is saturated above this there will be formation of super saturated solution.
3. Analyze the following graph and the following question regarding solubility of sugar in water.
materials-science-questions-answers-quiz-q3
a) Decrease with increase in temperature
b) Increase with increase in temperature
c) Increase with decrease in temperature
d) Remains constant with increase or decrease in temperature
Answer: b
Explanation: The solubility of sugar increases when the solution is heated.
4. What is a phase?
a) The substance which is physically distinct
b) The substance which is homogenous chemically
c) The substance which is both physically distinct and chemically homogenous
d) The substance which is both physically distinct and chemically heterogeneous
Answer: c
Explanation: A phase can be defined as a physically distinct and homogeneous chemically portion of a system that has a particular chemical composition and structure.
5. Which of the following portion of the given diagram contains only gas?
materials-science-questions-answers-quiz-q5
a) 1
b) 4
c) 5
d) 4, 5
Answer: c
Explanation: In the figure pure substances exists at 1, 3, 5 out of which 1 is given solid so 5 is pure gas.
6. Which of the following portion of the given diagram contains liquid in it?
materials-science-questions-answers-quiz-q5
a) 2, 3
b) 2, 4
c) 3, 4
d) 2, 3, 4
Answer: d
Explanation: From figure in process 2 the substance solid is being converted to liquid. In 3 only pure liquid exists. In 4 liquid is converting into solid. These all stages contain liquid in it.
7. Which of the following portion of given diagrams contains only pure substances?
materials-science-questions-answers-quiz-q5
a) 1, 3, 5
b) 1, 5
c) only 1
d) 3, 5
Answer: a
Explanation: Pure substances are substances that contain only a single phase such as solid or liquid or gas. These phases exist in 1, 3 and 5 portions.
.
8. Which of the following portion of the given diagram has a freezing section?
materials-science-questions-answers-quiz-q5
a) 1
b) 2
c) 3
d) 4
Answer: b
Explanation: Since this is a warming curve, this section indicates the melting temperature, but freezing point is identical to melting temperature. It can be noted as freezing range in a cooling curve.
9. Which of the following portion of the given graph has a boiling point?
materials-science-questions-answers-quiz-q5
a) 2
b) 3
c) 4
d) 5
Answer: c
Explanation: At this point the substance gets converted from liquid to gas.
10. Which of the following section given graph in which we use * * to calculate the energy change?
materials-science-questions-answers-quiz-q5
a) 2
b) 1, 3
c) 1, 3, 5
d) 2, 3, 5
Answer: c
Explanation: Since the phase of substance remains constant and there is change in temperature of substance.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Unary Phase Diagrams”.
1. Which of the following are examples of unary phase diagrams?
a) Cu-Ni phase diagram
b) Water phase diagram
c) Cu-Pd phase diagram
d) Mg-Db phase diagram
Answer:b
Explanation: The simplest phase diagram is the water which is a one component system.
2. What are the external parameters that affect the phase structure?
a) Temperature, Pressure
b) Temperature, Composition
c) Pressure, Composition
d) Temperature, Pressure, Composition
Answer: d
Explanation: The phase of the system changes accordingly with an increase or decrease in the above parameters.
3. What is the phase fraction of an alloy when it is one phase system?
a) 0.6
b) 0.8
c) 0.5
d) 1.0
Answer: d
Explanation: Urinary phase diagram is a phase diagram of a single component over a range of temperature-pressure. It may consist of one or more phases but its chemical composition remains the same.
4. What will be the phase composition of a phase system?
a) The composition of each phase is same throughout the phase diagram
b) The composition of each phase is different throughout the phase diagram
c) Contains more than one composition in the entire phase diagram
d) Varies from molecule to molecule
Answer: a
Explanation: The composition of each phase is the same throughout the phase diagram.
5. Which of the following remains constant in Unary phase diagrams?
a) Pressure
b) Temperature
c) Composition
d) Both pressure and temperature
Answer: c
Explanation: Since there is only one phase there will be only one substance.
6. Along the phase boundaries, the phases on either side will be in ______
a) Equal
b) Equilibrium
c) Different
d) Constant
Answer: b
Explanation: At phase boundary, the phase compositions will be the same.
7. What is a triple point?
a) All three states are in equilibrium
b) All three states are not in equilibrium
c) All three states don’t exist
d) All three states don’t exist and are not in equilibrium
Answer: a
Explanation: In triple point, all the states exist and are in equilibrium.
8. What is the temperature at triple point of water?
a) 288 K
b) 273.16 K
c) 298 K
d) 277 K
Answer: b
Explanation: At 273.16 k all the three phases of water will be in equilibrium.
9. What is pressure at a triple point of water?
a) 5.08×10 -3 atm
b) 6.04×10 -3 atm
c) 7.04×10 -3 atm
d) 6.44×10 -3 atm
Answer: b
Explanation: At 6.04×10 -3 atm all the three phases of water will be in equilibrium.
10. Which of the following is unary phase diagram?
a) materials-science-questions-answers-unary-phase-diagrams-q10a
b) materials-science-questions-answers-unary-phase-diagrams-q10b
c) materials-science-questions-answers-unary-phase-diagrams-q10c
d) materials-science-questions-answers-unary-phase-diagrams-q10d
Answer: a
Explanation: Unary phase diagram consists of only one substance.
This set of Materials Science Mcqs focuses on “Binary Phase Diagrams”.
1. How many components are present in binary phase system?
a) 3
b) 4
c) 2
d) 1
Answer: c
Explanation: In binary phase system there will be only two components.
2. The line above which the alloy is liquid is called __________
a) Solidus line
b) Tie line
c) Liquidus line
d) Lever line
Answer: c
Explanation: The liquidus line is the line above which the alloy is liquid. At the temperature just below this line crystal of solid solution start forming.
3. It can be noted that the two substances are soluble in each other in the entire range of compositions in both liquid and solid state. This kind of system is known as ___________
a) Binary phase system
b) Unary phase system
c) Multiple phase system
d) Isomorphous system
Answer: d
Explanation: Isomorphous phase diagram is the phase diagram in which the two components are soluble in each other over an entire range of composition in both solid and liquid phases.
4. What is the XY line in the given phase diagram?
materials-science-questions-answers-mcqs-q4
a) Lever line
b) Tie line
c) Solidus line
d) Liquidus line
Answer: b
Explanation: To find the composition of the individual phases in the two phase region, a line is drawn and its intercepts on the liquidus and solidus lines. This is called as tie line.
5. What is the α region in the given phase diagram?
materials-science-questions-answers-mcqs-q4
a) Homogeneous liquid solution
b) Semi solid solution
c) Vapor
d) Substitutional solid solution
Answer: d
Explanation: α-region is a substitutional solid solution of two components A and B. And the given phase diagram denotes the Cu-Ni phase diagram.
6. What is used for the determination of Phase amounts?
a) Tie line and Temperature–Composition Point
b) Lever line
c) Temperature–Composition Point
d) Pressure
Answer: b
Explanation: Lever rule is used to determine the relative amount of each phase in a mixture. It takes the help of a tie-line at a given temperature.
7. A 53% Ni Cu-Ni alloy is cooled from the liquid state to 1300°C. Calculate the % of liquid and solid at 1300°C.
a) 28, 72
b) 38, 62
c) 35, 65
d) 65, 35
Answer: b
Explanation: The tie line at 1300ﹾC intersects solidus at 58% Ni and liquidus at 45% Ni.
Apply the lever rule to get the liquid fraction
% Liquid = 100* / = 38%
%Solid = 100* / = 62% .
8. According to the given figure, which of the following is used to determine the amount of each phase in a mixture?
materials-science-questions-answers-mcqs-q8
a) Lever rule
b) Tie line
c) Solidus line
d) Liquidus line
Answer: a
Explanation: For two phase system lever rule helps i.e. the tie line must be utilized in conjunction with a procedure that is often called the lever rule.
9. What is the equation for liquid mass fraction of this given phase diagram?
materials-science-questions-answers-mcqs-q8
a) c α – c 0 / c α – c L
b) c 0 – c L / c α – c L
c) c α / c α – c L
d) c 0 / c α – c L
Answer: a
Explanation: C α is composition of solid, C L is composition of liquid, C 0 is composition of alloy.
10. What is the region between liquidus and solidus lines?
materials-science-questions-answers-mcqs-q8
a) Two-phase region where liquid and solid coexist
b) Solid region
c) Liquid region
d) Lava region
Answer: a
Explanation: The intermediate region between liquidus and solidus lines is the two-phase region where liquid and solid coexists.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Isomorphous Alloys”.
1. How many components are present in unary phase system?
a) 1
b) 2
c) 3
d) 4
Answer: a
Explanation: Unary phase systems which consist of a single component. Phase systems with two components are called binary systems and those with three are called ternary systems.
2. In a binary isomorphous system which of the following is true?
a) The two metals are completely miscible in each other in liquid as well as solid form
b) The two metals are completely immiscible in each other in liquid as well as solid form
c) The two metals are completely miscible in each other in liquid form only
d) The two metals are completely miscible in each other in solid form only
Answer: a
Explanation: In a binary isomorphous system, the two metals are completely miscible in each other in liquid as well as solid form.
3. The number of components are 2, the number of phases are 3 and degrees of freedom are 0. Then which of the following equilibrium is it?
a) Invariant
b) Univariant
c) Bivariant
d) Trivariant
Answer: a
Explanation: We can solve the above question by using Gibb’s phase rule. When the given values are put in the equation the value is obtained to be zero which makes the reaction invariant.
4. The number of components are 2, the number of phases are 2 and degrees of freedom are 1. Then which of the following equilibrium is it?
a) Invariant
b) Univariant
c) Bivariant
d) Trivariant
Answer: b
Explanation: We can solve the above question by using Gibb’s phase rule. When the given values are put in the equation the value is obtained to be one which makes the reaction univariant.
5. The number of components are 2, the number of phases is 1 and degrees of freedom are 2. Then which of the following equilibrium is it?
a) Invariant
b) Univariant
c) Bivariant
d) Trivariant
Answer: c
Explanation: We can solve the above question by using Gibb’s phase rule. When the given values are put in the equation the value is obtained to be two which makes the reaction bivariant.
6. An alloy 30 wt% Ni- 70wt % Cu at 1315 °C will lie in which state?
a) Solid state
b) Liquid state
c) Mixture of solid and liquid state
d) α state
Answer: b
Explanation: An alloy 30 wt% Ni- 70wt % Cu at 1315 °C will lie in the liquid state which we can observe from its phase diagram.
7. An alloy 30 wt% Ni- 70wt % Cu at 1095 °C will lie in which state?
a) Solid state
b) Liquid state
c) Mixture of solid and liquid state
d) α state
Answer: d
Explanation: An alloy 30 wt% Ni- 70wt % Cu at 1095 °C will lie in the region where it is in α state which can be observed from its phase diagram.
8. The copper-nickel system is an example of solid solution hardening.
a) True
b) False
Answer: a
Explanation: The above statement is true and the copper-nickel system is an example of solid solution hardening. Therefore changes are caused due to distortion in its lattice structure.
9. In a copper nickel system the tensile strength increases with an increase in the percentage of nickel in the alloy.
a) True
b) False
Answer: a
Explanation: The above statement is true. As nickel has more tensile strength than copper, the tensile strength of copper increases with the increase in the percentage of nickel in the alloy.
10. In which of the following the alloy is rapidly cooled?
a) Anealing
b) Coring
c) Hot working
d) Cold working
Answer: b
Explanation: Hot working, cold working and annealing are all processes in which the alloy will be heated. In coring the alloy is rapidly cooled down.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Eutectic Systems”.
1. What is the line that defines the solubility limit of A in B and B in A from the figure?
materials-science-questions-answers-eutectic-systems-q1
a) Solidus line
b) Liquidus line
c) Solvus line
d) Solidus line and Liquidus line
Answer: c
Explanation: In addition to liquidus and solidus lines there are two more lines on A and B which define the solubility limits B in A and A in B respectively. These are called solvus lines.
2. What is the point at which three phases coexist at point E?
materials-science-questions-answers-eutectic-systems-q1
a) Peritectic point
b) Eutectic point
c) Eutectoid point
d) Peritectoid reaction
Answer: c
Explanation: Eutectic reaction is the reaction in which the Liquid phase directly converts into two different solid phases at a constant temperature known as eutectic temperature.
3. The micro structure of hypoeutectic alloys at room temperature consists of ________
materials-science-questions-answers-eutectic-systems-q1
a) Proeutectic β and α
b) Eutectic mixture
c) Proeutectic β and eutectic mixture
d) Proeutectic α and eutectic mixture
Answer: d
Explanation: In hypoeutectic alloys the αphase solidifies first and the micro structure at RT consists of this αphase and the eutectic mixture.
4. Why Pb-Sn eutectic alloys are used for soldering purpose?
a) The melting point at eutectic point is maximum
b) The melting point at the eutectic point is minimum
c) The melting point at the eutectic point is constant
d) The boiling point at the eutectic point is maximum
Answer: b
Explanation: The melting point at the eutectic point is minimum. That’s why Pb-Sn eutectic alloys are used as solders. Al-Cu, Al-Si, Ag-Cu are other eutectic systems.
5. Crystals of which material begin to form at point a from the figure?
materials-science-questions-answers-eutectic-systems-q5
a) Crystals of proeutectic α
b) Crystals of proeutectic β
c) Crystals of eutectic
d) Crystals of proeutectic α and β
Answer: a
Explanation: While cooling a hypoeutectic alloy which is in a liquid state, the temperature drops continuously till liquidus point, a, at which crystals of proeutectic αbegins to form.
6. At point b, the α fraction is given by the lever rule as ________
materials-science-questions-answers-eutectic-systems-q5
a) mn/bn
b) bn/mn
c) ab/be
d) be/ab
Answer: b
Explanation: On further cooling the fraction of αincreases. At any point, b, in the two-phase region the α fraction is given by the lever rule as bn/mn.
7. The inflection in the cooling curve between points a and e is due to _________
materials-science-questions-answers-eutectic-systems-q7
a) Latent heat
b) Low temperature
c) High temperature
d) Specific heat
Answer: a
Explanation: Solidification of proeutectic αcontinues till the eutectic temperature is attained. The inflection in the curve between points a and e is due to latent heat.
8. At the eutectic point the eutectic reaction proceeds at a constant temperature as ________
materials-science-questions-answers-eutectic-systems-q7
a) F = 1
b) F = 0
c) F = 2
d) F = 3
Answer: b
Explanation: At the eutectic point the solidification of eutectic mixture begins through the eutectic reaction which proceeds at a constant temperature as F = 0 .
9. Any composition left of point c or right of point d will cool and solidify like a _______
materials-science-questions-answers-eutectic-systems-q7
a) Eutectic
b) Proeutectic
c) Eutectoid
d) Isomorphous system
Answer: d
Explanation: Any composition left of point c or right of point d will cool and solidify like an isomorphous system.
10. A 34.6% Pb-Sn alloy is cooled just below the eutectic temperature . What is the fraction of proeutectic α and eutectic mixture ?
a) 70% and 30%
b) 64% and 36%
c) 36% and 64%
d) 30% and 70%
Answer: b
Explanation: The eutectic point is at 61.9% Sn and α boundary is at 19.2% Sn. Apply the lever rule % proeutectic α = 100*/ = 64%
% = 100*/ = 36%.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Eutectoid and Peritectic Reactions”.
1. On heating, one solid phase results in another solid phase and a liquid phase during __________ reaction.
a) Eutectoid
b) Peritectic
c) Eutectic
d) Peritectoid
Answer: b
Explanation: Peritectic reaction is the reaction in which one solid phase converts into another solid phase and liquid at a constant temperature.
2. A first solid phase results in a second solid phase another third solid phase on cooling during __________ reaction.
a) Eutectoid
b) Peritectic
c) Eutectic
d) Peritectoid
Answer: a
Explanation: Eutectoid reaction is a reaction in which one phase is converted into two different phases at a constant temperature. Iron-carbon diagram is one of the examples of the Eutectoid phase diagram.
3. A first solid phase results in a second solid plus another third solid phase upon heating during __________ reaction.
a) Eutectoid
b) Peritectic
c) Eutectic
d) Peritectoid
Answer: d
Explanation: Here only the solid phase is involved and the product is also solid.
4. Which phase will crystallize first just below the liquidus line?
materials-science-questions-answers-eutectic-systems-q7
a) α phase
b) β phase
c) phase
d) phase
Answer: a
Explanation: The α phase will crystallize first because it is just below the liquidus line.
5. At what temperature, all liquid and α will convert to β?
materials-science-questions-answers-eutectic-systems-q7
a) Eutectic temperature
b) Peritectic temperature
c) Eutectoid temperature
d) Peritectoid temperature
Answer: b
Explanation: L + α → β, the above reaction is peritectic and takes place at peritectic temperature.
6. Any composition left and right of P will generate ___________
a) Excess of liquid and α
b) Excess of α and liquid
c) Excess of liquid and β
d) Excess of β and liquid
Answer: b
Explanation: Any composition left of P will generate excess α and similarly right of P will give rise to an excess amount of liquid.
7. Which of the following are Peritectic systems?
a) Pt – Ag
b) Ni – Re
c) Ni – Re, Fe – Ge, Sn-Sb
d) Pt – Ag, Ni – Re, Fe – Ge, Sn-Sb
Answer: d
Explanation: Peritectic systems – Pt – Ag, Ni – Re, Fe – Ge, Sn-Sb .
8. What is the eutectoid structure of Iron?
a) Cementite
b) Ferrite
c) Pearlite
d) Austentite
Answer: c
Explanation: It is important to be known that pearlite isn’t a phase, but a mixture of two phases: ferrite and cementite.
9. What is the maximum %C by weight in hypo-eutectoid steels?
a) 0.5%
b) 0.7%
c) 0.8%
d) 1.2%
Answer: c
Explanation: Steels with less than 0.8% carbon are known as hypo-eutectoid steels. Its micro-structural components are α-ferrite and pearlite.
10. The phase above eutectoid temperature for carbon steels is known as _______
a) Cementite
b) Ferrite
c) Pearlite
d) Austentite
Answer: d
Explanation: In the Fe-C system, there is a eutectoid point at 0.8wt% C, and temp of 723°C. The phase just above the eutectoid temperature for carbon steels is known as austeniteor gamma.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Gibbs Phase Rule”.
1. What is Gibbs phase rule for general system?
a) P = C – 1 – F
b) P = C + 1 – F
c) P + F = C – 2
d) P + F = C + 2
Answer: d
Explanation: The number of degrees of freedom, F , number of components, C, and number of phases in equilibrium, P.
2. What is Gibbs phase rule for metallurgical system?
a) F = C – 1 – P
b) F = C + 1 – P
c) P + F = C – 2
d) P + F = C + 2
Answer: b
Explanation: For metallurgical system pressure has no appreciable effect on phase equilibrium and hence, F = C – P + 1.
3. In a single – component condensed system, if degree of freedom is zero, maximum number of phases that can co – exist _________
a) 2
b) 3
c) 0
d) 1
Answer: a
Explanation: Given F = 0
Then p = c + 1, c = 1
.: P = 2.
4. The degree of freedom at a triple point in the unary diagram for water is ________
a) 2
b) 3
c) 0
d) 1
Answer: c
Explanation: For three phase system degree of freedom is 0.
5. What is degree of freedom for single – phase fields on the phase diagram?
a) 2
b) 3
c) 0
d) 1
Answer: a
Explanation: F = C + 1 – P
F = 3 – P
.:F = 2.
6. What is degree of freedom when two phases co – exist?
a) 2
b) 3
c) 0
d) 1
Answer: d
Explanation: F = C + 1 – P
F = 3 – P
F = 3 – 2 = 1.
7. What is degree of freedom when three phases co – exist?
a) 2
b) 3
c) 0
d) 1
Answer: c
Explanation: F = C + 1 – P
F = 3 – P
F = 3 – 3 = 0.
8. For single component system when degree of freedom is 1 then number of phases _______
a) 2
b) 3
c) 0
d) 1
Answer: d
Explanation: F = C + 1 – P
F = 2 – P
→ p = 2 – F = 2 – 1 = 1.
9. When α, L and β phase fields touch the isotherm line what are the respective phase compositions?
materials-science-questions-answers-gibbs-phase-rule-q8
a) 8.0 wt%, 71.9 wt%, 91.2 wt% of Ag
b) 8.0 wt%, 91.2 wt%, 71.9 wt% of Ag
c) 71.9 wt%, 91.2 wt%, 8.0 wt% of Ag
d) 91.2 wt%, 8.0 wt%, 71.9 wt% of Ag
Answer: a
Explanation: For binary systems, when three phases are present, there will be F = 0, so composition is fixed.
10. For binary alloy consisting of three phases of non – equilibrium one, What will be the temperature of these phases?
materials-science-questions-answers-gibbs-phase-rule-q8
a) Different
b) Constant
c) Same
d) Two of them will be with one temperature
Answer: c
Explanation: One use of the Gibbs phase rule is in analyzing for non – equilibrium conditions by analyzing with above method we come to know .
This set of Materials Science Question Bank focuses on “Iron-Carbon Systems”.
1. What is maximum solubility % of carbon and temperature range that α-ferrite exist?
materials-science-questions-bank-q1
a) 0.05% and 273°c to 910°c
b) 0.025% and 273°c to 910°c
c) 2.1% and 910°c to 1394°c
d) 0.05% and 910°c to 1124°c
Answer: b
Explanation: Interstitial solid solution of C in BCC iron. Max solubility of C is 0.025% and it exists from 273°C to 910°C.
2. What is maximum solubility % of carbon and temperature range that Austenite Ɣ exist?
materials-science-questions-bank-q1
a) 0.05% and 273°c to 910°c
b) 0.025% and 273°c to 910°c
c) 2.1% and 910°c to 1394°c
d) 0.09% and 1394°c to 1539°c
Answer: c
Explanation: Interstitial solid solution of C in FCC iron has a 2.1% max solubility of C and exists from 910°C – 1394°C.
3. What is maximum solubility % of carbon and temperature range that δ-ferrite exist?
materials-science-questions-bank-q1
a) 0.05% and 273°c to 910°c
b) 0.025% and 273°c to 910°c
c) 2.1% and 910°c to 1394°c
d) 0.09% and 1394°c to 1539°c
Answer: d
Explanation: δ-ferrite exists over the temperature range of 1394°C to 1539°C and the maximum solubility of C is 0.09%.
4. What is the % C content in Cementite (Fe 3 C)?
materials-science-questions-bank-q1
a) 6.67%
b) 0.025%
c) 2.1%
d) 0.09%
Answer: a
Explanation: It is an intermetallic compound. C content in Fe 3 C is 6.67%.
5. What is the hardest phase of Fe-C system?
materials-science-questions-bank-q1
a) Graphite
b) Bainite
c) Martensite
d) Cementite
Answer: d
Explanation: Cementite is the hardest phase in the Iron-Carbon system whereas martensite is not a phase because it is metastable in nature.
6. What is eutectoid temperature?
materials-science-questions-bank-q1
a) 727°c
b) 768°c
c) 1146°c
d) 1495°c
Answer: a
Explanation: The eutectoid temperature during heating and cooling is Ac1 and Ar1 respectively. Eutectoid reaction is a reaction that transforms one solid into two different solids on cooling.
7. At what temperature Fe turns paramagnetic while heating?
materials-science-questions-bank-q1
a) 727°c
b) 768°c
c) 1146°c
d) 1495°c
Answer: b
Explanation: At 768°C. Iron converts from ferromagnetic to paramagnetic and this temperature is known as curie temperature. It is also called as A 1 isotherm in iron carbon phase diagram.
8. What is the value of eutectic temperature?
materials-science-questions-bank-q1
a) 727°c
b) 768°c
c) 1146°c
d) 1495°c
Answer: c
Explanation: The eutectic temperature for Fe-C system is 1146°C. The eutectic reaction is a reaction that transforms one liquid phase into two solid phases on cooling.
9. What is the value of peritectic temperature?
materials-science-questions-bank-q1
a) 727°c
b) 768°c
c) 1146°c
d) 1495°c
Answer: d
Explanation: The peritectic temperature is at 1495°C for the Fe-C system. The peritectic reaction is a reaction that transforms one liquid and solid to another solid on cooling.
10. Carbon steel containing 9,1% ferrite is cooled from the region of austenitic . What is the percentage C content in the steel?
a) 0.05% C
b) 0.1% C
c) 0.2% C
d) 0.3% C
Answer: b
Explanation: Let c be Carbon content. Applying the lever rule
0.091 = /
c = 0.1% C.
This set of Materials Science online test focuses on “Phase Transformation Kinetics”.
1. What is/are the phenomenon involved in phase transformation?
a) Nucleation
b) Growth
c) Fission
d) Nucleation and growth
Answer: d
Explanation: Formation of a nucleus or tiny particles of the
new phase is nucleation and increase in size of the nucleus at the expense of the parent phase is growth.
2. How many types of nucleation process are there and what are they?
a) 2 and
b) 2 and
c) 2 and
d) 4 and
Answer: b
Explanation: Two types of nucleation – Heterogeneous and Homogeneous whereas fusion and fission are nuclear reactions.
3. What reactions come under supercooling?
a) Peritectic
b) Eutectic and Peritectic
c) Eutectic and Eutectoid
d) Peritectic and Eutectoid
Answer: c
Explanation: Driving force to nucleate increases as we increase T.
4. What are the characteristics of large supercooling in nucleation?
a) Few nuclei, large crystals
b) Rapid nucleation, many nuclei, small crystals
c) Rapid nucleation, many nuclei, large crystals
d) Few nuclei, small crystals
Answer: b
Explanation: Nuclei act as a template to grow crystals and for nucleus will help in a rate of the addition of atoms to the nucleus must be faster than the rate of loss.
5. At what temperature does supercooling is needed in homogeneous nucleation?
a) 0.1-10°C
b) 100- 250°C
c) 80-300°C
d) 10-15°C
Answer: c
Explanation: Nuclei form in the bulk of liquid metal so requires supercooling .
6. From the following figure if blue curve represent growth rate what does red and green curve represent respectively?
materials-science-questions-answers-online-test-q6
a) Nucleation rate, over all transformation rate
b) Over all transformation rate, Nucleation rate
c) Nucleation rate, finer grain size
d) Over all transformation rate, finer grain size
Answer: a
Explanation: The overall transformation rate is the product of nucleation and growth rates.
7. Which is the most important thermodynamic parameter in Homogenous nucleation?
a) Free energy G
b) Enthalpy H
c) Entropy S
d) Free energy G, Enthalpy H, Entropy S
Answer: a
Explanation: G is important as a phase transformation will occur immediately only when G has a negative value.
8. What does phase transformation involve?
a) Transformation rates kinetics
b) Movement/rearrangement of atoms
c) Changes in microstructure
d) Transformation rate kinetics, rearrangement of Atoms, Changes in microstructure
Answer: d
Explanation: Formation of a new phase having a
distinct physical/chemical character and a different structure than that of the parent phase.
9. Below the critical radius the tiny particles are _______ and are called _______
a) unstable, grains
b) stable, grains
c) unstable, embryo
d) stable, embryo
Answer: c
Explanation: The tiny particle of the solid that forms first will get stabilized only when it achieves a critical radius . Below the critical radius, it is considered unstable and is said to be an embryo.
This set of Materials Science online quiz focuses on “Phase Transformations in Iron-Carbon Systems”.
1. What is the Peritectic reaction at 1495°C?
a) L + δ → γ
b) L → γ + Fe 3 C
c) γ → α + Fe 3 C
d) L + δ → γ
Answer: a
Explanation: Peritectic reaction at 1495°C is
L + δ → γ.
2. What is the Eutectic reaction at 1146°C?
a) L + δ → γ
b) L → γ + Fe 3 C
c) γ → α + Fe 3 C
d) L + δ → γ
Answer: b
Explanation: Eutectic reaction at 1146°C is
L → γ + Fe 3 C .
3. What is Eutectoid reaction at 727°C?
a) L + δ → γ
b) L → γ + Fe 3 C
c) γ → α + Fe 3 C
d) L + δ → γ
Answer: c
Explanation: Eutectoid reaction at 727°C is
γ → α + Fe 3 C .
4. The eutectic mixture of austenite and cementite (Fe 3 C) is called __________
a) Ledeburite
b) Pearlite
c) Hyper and hypo eutectoid steel
d) Cast iron
Answer: a
Explanation: Eutectic reaction at 1146°C is
L → γ + Fe 3 C .
The eutectic mixture of austenite and cementite (Fe 3 C) is called Ledeburite.
5. The eutectoid mixture of ferrite and cementite (Fe 3 C) is called __________
a) Ledeburite
b) Pearlite
c) Hyper and hypo eutectoid steel
d) Cast iron
Answer: b
Explanation: The pearlite is formed under equilibrium
Conditions which consists of alternate lamellas or layers of ferrite and Fe 3 C.
6. Compositions right and left of 0.8% C of Pearlite are called __________
a) Ledeburite
b) Ferrite
c) Hyper and Hypoeutectoid steel
d) Cast iron
Answer: c
Explanation: Hypoeutectoid steels – α+ p; hypereutectoid – Fe 3 C + p.
7.Compositions above 2.1% C is called as _______
a) Ledeburite
b) Ferrite
c) Hyper and Hypoeutectoid steel
d) Cast iron
Answer: d
Explanation: Compositions up to 2.1% of Carbon are considered steels and beyond this it is considered as cast iron.
8. From the following figure if Diffusion rates below Ms is so low that γ → M transformation is a diffusionless process then what is change in crystal structure
materials-science-questions-answers-online-quiz-q8
a) FCC → BCT
b) FCC → BCC
c) BCC → BCT
d) BCT → BCC
Answer: a
Explanation: Diffusion rates below Ms is so low that γ → M transformationis a diffusion less process . However, the crystal structure changes from FCC to body centered tetragonal .
9.Finer size pearlite is called _______
a) Troostite
b) Ledeburite
c) Ferrite
d) Sorbite
Answer: d
Explanation: Finer size pearlite is called sorbite and very fine size pearlite is called troostite.
10. A eutectoid steel is slowly cooled from a temperature of 750°C to a temperature just below 727°C. Calculate the percentage of ferrite and cementite.
a) 88.3% and 11.7%
b) 70% and 30 %
c) 85.4% and 14.6%
d) 20% and 20%
Answer: a
Explanation: Eutectoid composition – 0.8% of Carbon,
Ferrite composition- 0.025% of Carbon and
cementite – 6.67% C.
Apply the lever rule to get the percentages as
% of Ferrite = 100/=88.3% ferrite
%of Cementite = 100/ =11.7%.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Time Temperature Transformation Curves”.
1. Time temperature transformation diagrams are drawn for ______________
a) Iron
b) Manganese
c) Any alloy
d) Only steel
Answer: d
Explanation: Time temperature transformation diagrams are drawn for only steels and only on steel of constant composition at a time is taken.
2. Which of the following is not a name for time temperature transformation diagrams?
a) S curve
b) C curve isothermal diagram
c) D curve isothermal diagram
d) Bain’s curve
Answer: c
Explanation: S curve, C curve isothermal diagram and Bain’s curve are all names given to time temperature transformation diagrams. D curve isothermal diagram is not a name given to it.
3. Steel with different carbon content shows different time temperature transformation diagrams.
a) True
b) False
Answer: a
Explanation: The above statement is true. Steel with different carbon content shows different time temperature transformation diagrams.
4. Which of the following phase will be resulted when the transformation temperature of steel is more than 750 °C?
a) Austenite
b) Pearlite
c) Bainite
d) Martensite
Answer: a
Explanation: At a temperature above 750 °C, the steel is in the form of austenite which is observed from a time temperature transformation diagram which shows the transformation time and temperature of transformation.
5. Which of the following phase will be resulted when the transformation temperature of steel is in the range of 500 °C to 750 °C?
a) Austenite
b) Pearlite
c) Bainite
d) Martensite
Answer: b
Explanation: At a temperature between 550 °C and 750° C, the steel is in the form of pearlite which is observed from a time temperature transformation diagram which shows the transformation time and temperature of transformation.
6. Which of the following phase will be resulted when the transformation temperature of steel is in the range of 300 °C to 550 °C?
a) Austenite
b) Pearlite
c) Bainite
d) Martensite
Answer: c
Explanation: At a temperature between 300 °C and 550°C, the steel is in the form of bainite which is observed from a time temperature transformation diagram which shows the transformation time and temperature of transformation.
7. Which of the following phase will be resulted when the transformation temperature of steel is in the range of 100 °C to 300 °C?
a) Austenite
b) Pearlite
c) Bainite
d) Martensite
Answer: d
Explanation: At a temperature 100 °C and 300°C, the steel is in the form of martensite which is observed from a time temperature transformation diagram which shows the transformation time and temperature of transformation.
8. Which of the following is the hardest?
a) Austenite
b) Pearlite
c) Bainite
d) Martensite
Answer: d
Explanation: Martensite is the hardest among the four followed by bainite and then pearlite. Austenite is the least hard among the following as it occurs at the highest temperature where the steel is soft.
9. To construct a TTT diagram, the specimen of steels is heated and then cooled.
a) True
b) False
Answer: a
Explanation: The above statement is true. To construct a time temperature transformation diagram, the specimen of steels is heated to a fixed temperature and then rapidly cooled.
10. In an isothermal curve, which of the following is true when the temperature is increased?
a) The curve shifts rightward
b) The curve shifts leftward
c) The curve goes down
d) The curve goes up
Answer: a
Explanation: In an isothermal curve with an increase in temperature the curve shifts towards the right and with a decrease in temperature the curve will shift towards left on the graph.
This set of Basic Materials Science Questions and Answers focuses on “Continuous Cooling Transformation Diagrams”.
1. Continuous cooling transformation diagrams are mainly drawn for _________
a) Iron
b) Manganese
c) Any alloy
d) steel
Answer: d
Explanation: Continuous cooling transformation diagrams are drawn for mainly steels and steel of constant composition at a time is taken.
2. In continuous cooling transformation diagrams, which of the following is true?
a) The material is cooled rapidly
b) The material is first heated and then cooled rapidly
c) The material is cooled at a certain rate
d) The material is kept at a constant temperature
Answer: c
Explanation: In a continuous cooling transformation diagrams, the material is cooled at a certain rate instead of heating and then cooling it rapidly and then maintaining a constant temperature in case of TTT diagrams.
3. How many types of CCT diagram are there?
a) 1
b) 2
c) 3
d) 4
Answer: b
Explanation: There are two types of continuous cooling transformation diagrams which can be drawn. In the two type, some factors are changed to obtain a different curve.
4. Which physical property is normally measured to determine a CCT diagram?
a) Hardness
b) Magnetic permeability
c) Pressure
d) Ductility
Answer: b
Explanation: CCT diagrams are determined by measuring magnetic permeability and specific volume during continuous cooling.
5. Slope change in a CCT diagram signify _________
a) Change in temperature
b) Change in pressure
c) Change in phase
d) Change in state
Answer: c
Explanation: When there is a slope change observed in a continuous cooling transformation diagram, it signifies that there is a change in phase occurring at that point.
6. Jominy end quench test is used for type 2 CCT diagram.
a) True
b) False
Answer: b
Explanation: The above statement is false. Jominy end quench test apart from its use in finding out hardenability of a material, it is also used for plotting type 1 CCT diagram.
7. Which of the following scientist gave a method to calculate the transformation temperature during continuous cooling?
a) Scheil’s
b) Newton
c) Jominy
d) Einstein
Answer: a
Explanation: Scheil gave a method which can be used to calculate the transformation temperature of a material during continuous cooling of the material. The concept is called Scheil’s concept of fractional nucleation.
8. Critical cooling rate required is less in CCT than in TTT diagrams.
a) True
b) False
Answer: a
Explanation: The above statement is true. In a continuous cooling transformation diagrams, the critical cooling rate is less than that prescribed in TTT diagrams.
This set of Tough Materials Science Questions and Answers focuses on “Mechanical Behavior of Iron-Carbon Alloys”.
1. In an iron carbon alloy, the mechanical properties are dependent on the micro structure.
a) True
b) False
Answer: a
Explanation: The above statement is true. In an iron carbon alloy, the mechanical properties are dependent on the micro structure.
2. Which of the following is present in pearlite?
a) Spherodite
b) Bainite
c) Ledeburite
d) Ferrite
Answer: d
Explanation: Pearlite consists of alternate layer of ferrite and cementite in which cementite is harder and more brittle as compared to ferrite.
3. Which of the following is true?
a) Fine pearlite is harder than coarse pearlite
b) Fine pearlite is softer than coarse pearlite
c) Fine pearlite is more ductile than coarse pearlite
d) Toughness of steel decreases with increase in carbon percentage
Answer: a
Explanation: Fine pearlite is harder than coarse pearlite, but coarse pearlite is more ductile than fine pearlite.
4. Which is the most tough among the steels given their carbon composition?
a) 0.1%
b) 0.2%
c) 1.5%
d) 2.5%
Answer: a
Explanation: The toughness of the steel decreases as we increase the carbon content and therefore 0.1% carbon which is lower than 1.5%, 0.2% and 2.5% is most tough among the options.
5. Which of the following is present in spherodite?
a) Pearlite
b) Bainite
c) Ledeburite
d) Ferrite
Answer: d
Explanation: Spherodite also consists of ferrite and cementite. In spherodite it cementite is present in a sphere structure in a matrix of ferrite.
6. Which of the following is present in bainite?
a) Ferrite
b) Bainite
c) Ledeburite
d) α-Ferrite
Answer: d
Explanation: Bainite steels consists of α-Ferrite and cementite and have a finer structure which makes then stronger than pearlite steel.
7. Which among the following is the strongest?
a) Austenite
b) Pearlite
c) Bainite
d) Martensite
Answer: d
Explanation: Among all the structure martensite has the strongest structure. It is the hardest and most brittle among the microstructure.
8. In which of the following steels there is a chance of quenching cracks being formed?
a) 0.2% carbon
b) 0.4% carbon
c) 0.5% carbon
d) 0.6% carbon
Answer: d
Explanation: If the carbon content in a steel is higher than 0.5 %, during quenching there can be a formation of quenching cracks.
9. At what temperature is martensite heated in tempering?
a) 727
b) 627
c) 327
d) 927
Answer: a
Explanation: The martensitic steel is tempered in the temperature of 650–800°C to get optimum mechanical properties that includes ductility and toughness.
10. Tempered martensite has better ductility than martensite.
a) True
b) False
Answer: a
Explanation: Tempered martensite has better ductility than martensite due to tempering. The hardness of the two is nearly the same.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Types of Metal Alloys”.
1. Which of the following is an alloy of iron?
a) Vitallium
b) Brass
c) Invar
d) Solder
Answer: c
Explanation: Invar is an alloy of iron. In this the alloying element is nickel and this alloy has a very low coefficient of thermal expansion.
2. Which of the following is an alloy of lead?
a) Vitallium
b) Brass
c) Invar
d) Solder
Answer: d
Explanation: Solder is an alloy of lead. The alloying element is tin mainly, it is used for electrical connection by melting and fusing to form a permanent bond between two metal pieces.
3. Which of the following is an alloy of cobalt?
a) Vitallium
b) Brass
c) Invar
d) Solder
Answer: a
Explanation: Vitallium is an alloy of cobalt. The alloying elements are chromium and molydenum. It is used for components of turbochargers because of its high thermal resistance.
4. Which of the following is an alloy of copper?
a) Vitallium
b) Brass
c) Invar
d) Solder
Answer: b
Explanation: Brass is an alloy of copper. The alloying element in brass is zinc. It is used for making a variety of ornaments.
5. Which of the following is not a non-ferrous metal?
a) Aluminium
b) Lead
c) Zinc
d) Iron
Answer: d
Explanation: Ferrous metals are metals or alloys which contain iron as an element in it. Therefore cast iron is the only ferrous metal among the given options.
6. What are alloys with two components called?
a) Binary alloy
b) Ternary alloy
c) Quaternary alloy
d) There is no name given to an alloy with two components
Answer: a
Explanation: Alloys with two components are called binary alloy, while those with three components are called ternary alloy and alloys with 4 components are called quaternary alloy.
7. Substitutional alloy and interstitial alloys are types of alloys.
a) True
b) False
Answer: a
Explanation: The above statement is true. Substitutional alloy and interstitial alloys are types of alloys.
8. What is sterling silver used for?
a) casting of firearms
b) used for making musical instruments
c) used for making springs
d) used for joining two metals
Answer: b
Explanation: Sterling silver is an alloy which is used for making musical instruments such as flute and saxophone. It is also used for making cutlery.
9. Bronze is used for making medals.
a) True
b) False
Answer: a
Explanation: Bronze is an alloy with base metal as copper and is used for making medals and some musical instruments.
10. Which of the following alloy is used for making castings of firearm chamber?
a) Brass
b) Wood’s metal
c) Brass
d) Steel
Answer: b
Explanation: Wood’s metal is used for making a casting of firearm chambers by the maker of guns.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Steels”.
1. Which of the following is an alloy of iron and carbon?
a) Steel
b) Brass
c) Bronze
d) Solder
Answer: a
Explanation: Steel is an alloy of iron and carbon while solder, bronze and brass are alloys of different metal other than iron.
2. Which of following crystalline form can iron not take?
a) BCC
b) FCC
c) HCP
d) It can take all crystalline forms
Answer: c
Explanation: The correct answer is HCP or hexagonal close packing. Iron can take the crystalline structure of BCC and FCC according to the temperature.
3. Which of the following can be the carbon weight percentage in steel?
a) 2%
b) 5%
c) 3%
d) 4%
Answer: a
Explanation: In a typical steel, the carbon may contribute the maximum of 2.14% of the weight of the alloy. Therefore only 2% lies within the range and hence is the correct answer.
4. Which of the following cannot be used as an alloying element in steel?
a) Lead
b) Chromium
c) Nickel
d) Tungsten
Answer: a
Explanation: Lead cannot be used as an alloying element in steel. While chromium, nickel and tungsten are used as an alloying element in steel according to which the carbon percentage in the steel is found out.
5. Traces of which of the following element is considered undesirable in steel?
a) Chromium
b) Copper
c) Boron
d) Titanium
Answer: b
Explanation: Traces of copper, oxygen and nitrogen are undesirable in a steel alloy whereas chromium, boron and titanium are common alloying elements of steel alloy.
6. Which of the following element is added to steel to form stainless steel?
a) Chromium
b) Copper
c) Boron
d) Titanium
Answer: a
Explanation: Chromium is added to steel to inhibit corrosion and in a quantity of at least 11%. An oxide protection is formed on the surface of the steel, the alloy thus formed is called stainless steel.
7. At room temperature which is the most stable form of iron?
a) Pearlite
b) Ledeburite
c) Martensite
d) α-iron
Answer: d
Explanation: At room temperature, the most stable form of iron is BCC structure which is also called as α-iron.
8. When steel with exactly 0.8% carbon by weight is cooled, the FCC structure of the mixture tries to revert back to its BCC structure.
a) True
b) False
Answer: a
Explanation: The above statement is true. When steel with exactly 0.8% carbon by weight is cooled, the FCC structure of the mixture tries to revert back to its BCC structure.
9. Adding a nickel to the steel alloy increases its tensile strength.
a) True
b) Fasle
Answer: a
Explanation: The above statement is true. Nickel is added to the steel alloy to increase its tensile strength and make its austenite structure more stable.
10. Which of the following can be the density of steel?
a) 8.1 g/cm 3
b) 7.8 g/cm 3
c) 7.7 g/cm 3
d) 8.2 g/cm 3
Answer: b
Explanation: The density of steel varies between 7.75 g/cm 3 and 8.05 g/cm 3 . As only 7.8 g/cm 3 lies in that range and the others are beyond the range, 7.8 g/cm 3 is the correct answer.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Cast Irons”.
1. Which of the following can be carbon composition of cast iron?
a) 1%
b) 1.5%
c) 0.5%
d) 2.5%
Answer: d
Explanation: The carbon composition in cast iron is more than 2% and hence only 2.5% can be correct answer as all the answer lie outside the range.
2. Cast iron tends to be brittle.
a) True
b) False
Answer: a
Explanation: The above statement is correct. Cast iron tends to be brittle because of the presence of a high amount of carbon in it.
3. At what temperature does pure iron turn into FCC structure?
a) 800 °C
b) 900 °C
c) 910 °C
d) 810 °C
Answer: c
Explanation: Pure iron turns into its FCC structure at a temperature of 910 °C. This structure is called gamma iron or γ-iron.
4. Which of the following alloying element forces the carbon out of the solution?
a) Silicon
b) Sulphur
c) Nickel
d) Titanium
Answer: a
Explanation: Silicon is used in a cast iron to bring out the carbon from the solution. If a large amount silicon is added grey cast iron is formed.
5. Which of the following alloying element increase hardness?
a) Silicon
b) Sulphur
c) Nickel
d) Titanium
Answer: b
Explanation: The presence of sulfur increase the hardness of the alloy by reacting with iron to form iron sulphide.
6. Which of the following alloying element refines pearlite structure?
a) Silicon
b) Sulphur
c) Nickel
d) Titanium
Answer: c
Explanation: Nickel is the most common alloying element in cast iron. It helps in refining the pearlite and graphite structure.
7. Which of the following alloying element is added as a degasser?
a) Silicon
b) Sulphur
c) Nickel
d) Titanium
Answer: d
Explanation: Titanium is added as a degasser and it increases the fluidity of the alloy and it also acts as a deoxidiser.
8. Due to the presence of which of the following does white cast iron appear white?
a) Pearlite
b) Ledeburite
c) Martensite
d) Cementite
Answer: d
Explanation: In white cast iron, it appears as a broken white surface due to the presence of cementite which is a metastable phase.
9. In malleable cast iron, the graphite turns into spheroidal particles.
a) True
b) False
Answer: a
Explanation: The above statement is true. In malleable cast iron, the graphite turns into spheroidal particles rather than forming flakes.
10. What is the form graphite structure in ductile cast iron?
a) Spheroidal
b) Nodular
c) Flakes
d) Layers
Answer: b
Explanation: The graphite structure of a ductile cast iron is nodular form and it is seen as tiny nodules with graphite in layers forming the nodules.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Non-ferrous Alloys”.
1. Which of the metal if present will make the alloy ferrous?
a) Aluminium
b) Lead
c) Zinc
d) Iron
Answer: d
Explanation: Ferrous metals are metals or alloys which contain iron as an element in it. Therefore Iron is the only ferrous metal among the given options presence of which will make the alloy ferrous.
2. Which of the following is costliest among the non ferrous materials?
a) Magnesium
b) Aluminum
c) Titanium
d) Copper
Answer: c
Explanation: Titanium is the costlier than magnesium, aluminum and copper. This is why titanium has limited application even though it has strength to weight ratio and corrosion resistance.
3. Which of the following is the lightest among the following?
a) Magnesium
b) Aluminum
c) Titanium
d) Copper
Answer: b
Explanation: Aluminum is the lightest among magnesium, titanium and copper. As it is light, it is used at a variety of places.
4. Which of the following element when alloyed with magnesium does not reduce the tendency to crack under stress?
a) Aluminum
b) Silicon
c) Zinc
d) Copper
Answer: d
Explanation: The correct answer is copper. Aluminum, silicon and zinc are alloyed with magnesium to reduce the tendency of magnesium to crack under stress.
5. Which of the following is an alloy of tin?
a) Brass
b) Bronze
c) Pewter
d) Steel
Answer: c
Explanation: Pewter is an alloy of 85 % – 99 % of tin with alloying elements like copper and lead traces.
6. Which of the metal is alloyed with silver to make sterling silver?
a) ZInc
b) Copper
c) Magnesium
d) Aluminum
Answer: b
Explanation: Sterling silver is an alloy of silver to reduce its cost. It is an alloy with 90% of silver and 10% copper.
7. Tin has low viscosity.
a) True
b) False
Answer: a
Explanation: The above statement is true. Tin has low viscosity and therefore is a good material for casting application.
8. Which of the following metal highly prone to corrosion?
a) Aluminum
b) Copper
c) Iron
d) Zinc
Answer: d
Explanation: Zinc is an element that is highly prone to corrosion. Therefore, it is used as a sacrificial anode or in galvanization.
9. Monel is an alloy of nickel.
a) True
b) False
Answer: a
Explanation: The above statement is true. Monel is an alloy in which major element is nickel in which copper is added. Magnesium and iron can be added with a limit of 2% and 2.5 % respectively.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Metal Fabrication Techniques”.
1. Which of the following is a method of applying a protective zinc coating to steel?
a) Galvanizing
b) Glazing
c) Hydroforming
d) Metal punching
Answer: a
Explanation: Galvanizing is a process in which a zinc coating is applied over the steel or iron sources to help prevent corrosion.
2. Which of the following is a process in which two metal slide against each other?
a) Galvanizing
b) Glazing
c) Hydroforming
d) Metal punching
Answer: b
Explanation: The correct answer is glazing. In glazing, teo metals are made to slide against each other so that a shiny oxide layer is formed over the metal surfaces which will protect it from further wear.
3. Which of the following is a method in which high pressurized fluid is used?
a) Galvanizing
b) Glazing
c) Hydroforming
d) Metal punching
Answer: c
Explanation: Hydroforming is a type of forming in which a special die is used which uses high pressurized fluid to give shape to metals and metal alloys like steel, copper and brass.
4. Which of the following is a process in holes are punchedl?
a) Galvanizing
b) Glazing
c) Hydroforming
d) Metal punching
Answer: d
Explanation: Metal punching is the correct answer. It is a process in which a machine is used to punch a hole or a predetermined shape is punched out of the sheet metal.
5. Milling uses rotatory cutters.
a) True
b) False
Answer: a
Explanation: The above statement is true. Milling is a process which uses rotatory cutters to remove material from a piece of metal which moves in a direction at an angle to the axis of the tool.
6. Which of the following a process in which material is made to pass through a roll?
a) Blanking
b) Cutting
c) Roll forming
d) Welding
Answer: c
Explanation: Roll forming is a method in which materials in the form of coins, bars or strips are made to pass through rolls that by constant bending form the metal.
7. Which of the following a process in which a part or shape is the cutout of the sheet metal?
a) Blanking
b) Cutting
c) Roll forming
d) Welding
Answer: a
Explanation: Blanking is the correct answer. Blanking is a process in which a part of a metal sheet is cut out of the sheet and the remaining material is discarded.
8. Which of the following a process in which sawing and shearing are used?
a) Blanking
b) Cutting
c) Roll forming
d) Welding
Answer: b
Explanation: The process in which sawing and shearing are used is cutting. It is processed in which a part is cut out using power tools or CNC or by manually using saws and chisel.
9. Which of the following a process is used to join two metals?
a) Blanking
b) Cutting
c) Roll forming
d) Welding
Answer: d
Explanation: Welding is a process which is used to join two metals using heat and sometimes pressure by melting the metals. It is a permanent joint and the joint will have to be broken to separate it again.
10. Shrinking is a process of making the metal smaller by applying force.
a) True
b) False
Answer: b
Explanation: The above statement is false. Shrinking is a process which is used to remove dents in which direct damage is not severely stretched.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Thermal Processing Techniques”.
1. Which of the following is an application of cold working?
a) Extrusion
b) Forging
c) Hot rolling
d) Deep drawing
Answer: d
Explanation: In all the other option the metal is heated over the recrystallization and hence they are hot worked.
2. Which is the correct order of temperature arranged in ascending order of the following processes?
i. Partial annealing
ii. Full annealing
iii. Subcritical annealing
a) iii, i, ii
b) ii, iii, i
c) iii, ii, i
d) i, iii, ii
Answer: a
Explanation: Full annealing is done at a temperature higher than upper critical temperature while partial annealing is done at a temperature in between upper critical temperature and lower critical temperature and subcritical annealing is done at a temperature below lower critical temperature.
3. Which of the following can be recrystallization temperature for a pure metal?
a) 0.3 Tm
b) 0.45 Tm
c) 0.35 Tm
d) 0.4 Tm
Answer: c
Explanation: Recrystallization temperature of a pure metal lies in the temperature of 0.3 to 0.4 Tm. Here, 0.35 Tm lies in the required range.
4. What does the term soaking signify?
a) Heating to a required temperature
b) Holding at a constant temperature
c) Cooling the material
d) Heating for a long time
Answer: b
Explanation: Soaking is a term used in annealing in which the material is hold at a constant temperature after heating to a required temperature.
5. Which of the following will not happen when metal is cooled fast in annealing?
a) Warping of material
b) Cracking of material
c) Formation of thermo elastic stresses
d) Strength increase
Answer: d
Explanation: A material in annealing is cooled slowly to avoid warping of the material, cracking of the material due to the formation of thermal gradients and thermo elastic stresses inside the body.
6. In process annealing, heating is limited to avoid excessive oxidation.
a) True
b) False
Answer: a
Explanation: In process annealing, the material is heated to revert the effects of work hardening by recovery and recrystallization and heating is done in such a way that excessive grain growth and oxidation can be avoided.
7. Which of the following does not happen when a material is annealed?
a) Internal stresses get relieved
b) Increase in ductility
c) Decrease in toughness
d) Increase in softness
Answer: c
Explanation: A material is annealed to relieve internal stresses, increase ductility, toughness and softness and produce specific microstructure.
8. Which material is present above the upper critical temperature line in an iron carbon phase diagram?
a) Martensite
b) Pearlite
c) Ledeburite
d) Austenite
Answer: d
Explanation: Above the upper critical line in a iron carbon phase diagram, all the material is austenite while below the lower critical no austenite material exists.
9. In stress relief annealing, the annealing temperature is relatively low.
a) True
b) False
Answer: a
Explanation: The above statement is true. Annealing temperatures are low in stress relief annealing so that the useful effects of cold working are not eliminated.
10. Which of the following is not a type of annealing?
a) Spherodizing
b) Tempering
c) Full annealing
d) Stress-relief annealing
Answer: b
Explanation: Tempering is used to increase hardness by reheating and cooling the material which is not a type of annealing. Full annealing, Spherodizing and Stress-relief annealing are types of annealing.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Heat Treatment of Steels”.
1. Which of the following alloying element can be used to deoxidize steels?
a) Phosphorous
b) Carbon
c) Cerium
d) Selenium
Answer: c
Explanation: Cerium, calcium, magnesium, manganese and titanium can be used to deoxidise steel.
2. Which of the following processes will one use on hardened steel to reduce brittleness?
a) Annealing
b) Normalizing
c) Spheroidizing
d) Tempering
Answer: d
Explanation: Tempering is a process of heating to lower critical temperature, then maintaining it at temperature followed by slow cooling to relieve stress and reduce brittleness, increase ductility.
3. Which of the following material in the final structure of steel increases the strength of steel?
a) Martensite
b) Pearlite
c) Ledeburite
d) Austenite
Answer: a
Explanation: The amount of martensite remaining in the final structure is correlated with the strength of the steel.
4. Which of the following is defined as the ability of the structure to transform into martensite?
a) Hardenability
b) Strength
c) Toughness
d) Hardness
Answer: a
Explanation: Hardenability is defined as the ability of the structure to transform into martensite.
5. Which of the following has the highest hardness number?
a) Martensite
b) Tempered martensite
c) Pearlite
d) Fine pearlite
Answer: a
Explanation: Martensite is the hardest and the most brittle microstructure of steel. It has a higher hardness number than tempered martensite, fine pearlite and pearlite. Tempered martensite is harder than fine pearlite.
6. Jominy end-quench test is used to determine the hardness of a material.
a) True
b) False
Answer: b
Explanation: Jominy end-quench test is a test used on a material by quenching using a jet of water to determine the hardenability of the material.
7. In a hardnability curve which of the following is true:
a) Hardness increases as distance from quenched end increases
b) Hardness decreases as distance from quenched end increases
c) Hardness increases as martensite decreases
d) Hardenability curve is a straight line
Answer: b
Explanation: In a hardenability curve, which is made by keeping hardness number on y-axis and distance from a quenched end at the x-axis. The hardness number decrease as the distance from the quenched end increases.
8. Which of the following is formed less when cooling rate is decreased?
a) Pearlite
b) Fine pearlite
c) Bainite
d) Martensite
Answer: d
Explanation: As the cooling rate decreases with increase of distance from the quenched end, more pearlite and bainite is formed and therefore hardness number decreases.
9. Hardness number decreases with an increase in carbon content in steel.
a) True
b) False
Answer: b
Explanation: The above statement is false. The hardness number increase with the increase in the carbon content in steel as more martensite is formed with the increase in carbon content.
10. Which of the following statement is false?
a) Greater ratio of surface area to volume, more the hardening effect
b) Cooling is faster in water than oil
c) Spheres cool faster than irregular shaped objects
d) Precipitation hardening can also be called age hardening
Answer: c
Explanation: The statements greater ratio of surface area to volume, more the hardening effect, cooling is faster in water than oil and precipitation hardening can also be called age hardening are true. Spheres cool slower than irregular shaped object.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Crystal Structure of Ceramics”.
1. Which of the following is false about ceramic structures?
a) They are made up of two or more different elements
b) More complex than metal structures
c) They are electrically neutral
d) Less complex than metal structures
Answer: d
Explanation: Ceramic structures are electrically neutral, more complex than metallic structures and are made up of two or more different elements.
2. Which of the following bonds are present in ceramic structures?
a) Ionics bonds only
b) Covalent bonds only
c) Ionic, covalent and a mix of ionic and covalent bond
d) Mix of ionic and covalent bond only
Answer: c
Explanation: Ceramic structures have ionic bonds, covalent bonds. They show a mix of covalent and ionic bonds in some cases.
3. What is the cation to anion ratio for a ceramic having coordination number 2?
a) <0.155
b) 0.155-0.225
c) 0.414-0.732
d) 0.732-1.0
Answer: a
Explanation: The cation to anion ratio for a ceramic having coordination number 2 is less than 0.155. For the given coordination number, the coordination geometry is also fixed.
4. What is the cation to anion ratio for a ceramic having coordination number 3?
a) <0.155
b) 0.155-0.225
c) 0.414-0.732
d) 0.732-1.0
Answer: b
Explanation: The cation to anion ratio for a ceramic having coordination number 3 lies in the range of 0.155 to 0.225. For the given coordination number, the coordination geometry is also fixed.
5. What is the cation to anion ratio for a ceramic having coordination number 6?
a) <0.155
b) 0.155-0.225
c) 0.414-0.732
d) 0.732-1.0
Answer: c
Explanation: The cation to anion ratio for a ceramic having coordination number 6 lies in the range of 0.414 to 0.732. For the given coordination number, the coordination geometry is also fixed.
6. What is the cation to anion ratio for a ceramic having coordination number 8?
a) <0.155
b) 0.155-0.225
c) 0.414-0.732
d) 0.732-1.0
Answer: d
Explanation: The cation to anion ratio for a ceramic having coordination number 8 lies in the range of 0.732 to 1.0. For the given coordination number, the coordination geometry is also fixed.
7. Which of the following compounds have a coordination number of 8?
a) Cesium chloride
b) Sodium chloride
c) Zinc blende
d) Calcium fluoride
Answer: a
Explanation: Cesium chloride has a coordination number of 8 while coordination number of sodium chloride and zinc blende are 6 and 4 respectively. Calcium chloride has a different coordination number for its anion and cation.
8. The coordination number of fluorine in calcium fluoride is?
a) 8
b) 6
c) 2
d) 4
Answer: d
Explanation: The calcium atoms are in the center and the fluorine atoms are at the corners of the cube and therefore only half sites are filled with calcium atoms and coordination number of fluorine id 4 and that of calcium is 8.
9. The geometry of a material with coordination number 6 is a tetrahedron.
a) True
b) False
Answer: b
Explanation: The above statement is false. The geometry of a material with coordination number 6 is octahedron and tetrahedron is the geometry of a material with coordination number 4.
10. Cesium chloride has an FCC structure.
a) True
b) False
Answer: b
Explanation: The above statement is false. Cesium chloride has a simple cubic structure with a coordination number of 8.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Silicate Ceramics”.
1. Which of the following is an aluminosilicate?
a) Steatite
b) Cordierite
c) Forsterite
d) Porcelain
Answer: d
Explanation: Porcelain is a type of aluminosilicate. They are kaolin or clay based ceramics.
2. Which of the following is magnesium silicates?
a) Porcelain
b) Earthenware
c) Stoneware
d) Steatite
Answer: d
Explanation: Steatite is a magnesium silicate. Magnesium silicates are talc based ceramics.
3. According to the percentage of water absorption in dense silicate ceramic which of the following is has fine microstructure?
a) 1%
b) 3%
c) 4%
d) 5%
Answer: a
Explanation: For a dense silicate ceramic, water absorption percentage should be less than 2% for fine structure and less than 6% for coarse structure.
4. There are ceramics which are electric resistant.
a) True
b) False
Answer: a
Explanation: The above statement is true. There are mullite based fine silicates which are used as electrical insulator.
5. According to the percentage of water absorption in porous silicate ceramic which of the following has fine microstructure?
a) 1%
b) 1.9%
c) 0.4%
d) 2.1%
Answer: d
Explanation: For a porous silicate ceramic, water absorption percentage should be greater than 2% for fine structure and greater than 6% for coarse structure.
6. Which of the following is the firing temperature of earthenware?
a) 1400 °C
b) 1300 °C
c) 1500 °C
d) 1200 °C
Answer: d
Explanation: The firing temperature commonly used for hard earthenware is 1200 °C. It can lie in a range of +50 °C and -50 °C that is 1150 °C and 1250 °C respectively.
7. Which of the following is firing temperature of hard porcelain?
a) 1400 °C
b) 1300 °C
c) 1500 °C
d) 1200 °C
Answer: a
Explanation: The firing temperature commonly used for hard porcelain are 1400 °C. It can lie in a range of +50 °C and -50 °C that is 1350 °C and 1450 °C respectively.
8. Which of the following is the firing temperature of stoneware?
a) 1400 °C
b) 1300 °C
c) 1500 °C
d) 1200 °C
Answer: d
Explanation: The firing temperature commonly used for stoneware is 1250 °C. It can lie in a range of +50 °C and -50 °C that is 1200 °C and 1300 °C respectively. Therefore 1200 °C is the correct answer.
9. Brick having high porosity will have the ability to resist frost.
a) True
b) False
Answer: b
Explanation: The above statement is false. As the ability to resist frost in a brick is observed in bricks having low porosity and thermal insulation is observed in bricks with high porosity.
10. Which of the following is not a component of steatite ceramic?
a) Talc
b) Clay
c) Feldspar
d) MgCO 3
Answer: d
Explanation: Steatite is ceramic composed of talc and clay which common for all magnesium ceramics. Along with that, it has feldspar which is also BaCO 3 . Hence it does not contain MgCO 3 .
This set of Materials Science Multiple Choice Questions & Answers focuses on “Carbon”.
1. Carbon is a ceramic.
a) True
b) False
Answer: b
Explanation: The above statement is false. Carbon is not a ceramic material. An allotropic form of carbon called diamond can be considered as a ceramic.
2. What kind of bonds are present in diamond?
a) Covalent bond only
b) Ionic bond only
c) Mix of covalent and ionic bond
d) Metallic bonds
Answer: a
Explanation: Diamonds have only carbon-carbon bonds which are covalent in nature.
3. Which of the following materials can be used as a substitute ceramic?
a) Diamond
b) Brass
c) Bismuth
d) Lead
Answer: a
Explanation: Diamond has properties resembling that of ceramics and hence can be used as a substitute ceramic. All the other options are metals and hence they can never be used as a ceramic.
4. What is a difference between carbon and ceramic?
a) Both are hard
b) Both are non metallic
c) Both have covalent bonds
d) Both have very high thermal conductivity
Answer: d
Explanation: Diamond has a very high thermal conductivity and doesn’t melt even at high temperature whereas ceramics do not have a high thermal conductivity.
5. Which of the following processes I not needed for making a synthetic diamond?
a) Application of high temperature
b) Application of high pressure
c) Chemical vapor deposition
d) Distillation
Answer: d
Explanation: To make a synthetic diamonds, application of high temperature and pressure is used. Chemical vapor deposition can also be used to make synthetic diamonds.
6. Which of the following can be used for lubrication?
a) Graphite
b) Diamond
c) Brass
d) Bronze
Answer: a
Explanation: Graphite due to its weak Vander Waals bonding between layers can be used as a lubricating agent.
7. Graphite is a good conductor of electricity.
a) True
b) False
Answer: a
Explanation: The above statement is true. Graphite is indeed a good conductor of electricity and it is chemically stable at even high temperatures.
8. The chemical composition of Buckminster Fullerene?
a) C60
b) C50
c) C55
d) C45
Answer: a
Explanation: The chemical composition of Buckminster Fullerene is C60. It is an allotropic form of carbon also called as Bucky-ball.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Imperfection in Ceramics”.
1. In which of the following defect the density of the crystal is affected?
a) Schottky defect
b) Frenkel defect
c) Stone-Wales defect
d) Antisite defect
Answer: a
Explanation: The density of the solid crystal in case of Schottky defect is less than the theoretical density of the material. This happens as the total number of ions in the lattice is less than the theoretical number of ions according to its volume, when this defect occurs.
2. Schottky and Frenkel defects are __________
a) interstitial and vacancy defects respectively
b) vacancy and interstitial defect respectively
c) interstitial defects
d) vacancy defects
Answer: b
Explanation: Schottky defect occurs when oppositely charged ions leave the crystal and creating a vacancy and hence is a vacancy defect while in Frenkel defect an atom moves from it’s original site to an interstitial position and hence is an interstitial defect.
3. Frenkel defects change the ratio of cation to anions.
a) True
b) False
Answer: b
Explanation: The above statement is false. Frenkel and Schottky’s defects do not change the ratio of cations and anions. The compound is stoichiometric.
4. In which of the following iron compounds, the compound is non-stoichiometric?
a) Fe 2+ and Fe 3+
b) Fe 2+ ion only
c) Fe 3+ ion only
d) It doesn’t depend on the iron ions
Answer: a
Explanation: A compound is non- stoichiometric when there is presence of the same ion in two valence state in the compound. In this case that is Fe 2+ and Fe 3+ .
5. In which of the following the concentration of defect is constant?
a) Point defect
b) Intrinsic defect
c) Extrinsic defect
d) Linear defect
Answer: c
Explanation: The concentration of defect is constant in case of extrinsic defect. For example Rock salt structure like Nacl and MgO.
6. In which of the following the concentration of defect increases with temperature increase?
a) Point defect
b) Intrinsic defect
c) Extrinsic defect
d) Linear defect
Answer: b
Explanation: The concentration of intrinsic defect increase with an increase in its temperature.
7. Which of the following does point defect does not depend on?
a) Density
b) Melting point
c) Hardness
d) Optical absorb
Answer: c
Explanation: Point defects do not depend on the hardness of the material and it depends on density, optical absorb and the melting point of the material.
8. Transition metal oxides are highly defective.
a) True
b) False
Answer: a
Explanation: The above statement is true. Transition metal oxides like NiO and FeO are often highly defective.
This set of Materials Science Assessment Questions and Answers focuses on “Stress-Strain Behavior in Ceramics”.
1. Ceramics are brittle.
a) True
b) False
Answer: a
Explanation: The above statement is true. Ceramics are generally not used in place of metals as they are brittle and their stress-strain characteristics are undesirable.
2. Which of the following test are done to find out the mechanical behavior of ceramics?
a) Tensile test
b) Compressive test
c) Shearing test
d) Transverse bending test
Answer: d
Explanation: Transverse bending test is performed on the material to find out its mechanical behavior. Tensile and compressive tests cannot be performed on them as they crack when gripped.
3. What is shape of a stress strain curve for ceramics?
a) Parabola
b) Hyperbola
c) Straight line
d) Inverted parabola
Answer: c
Explanation: The stress strain curve for a ceramic is a straight line as after a point the ceramic suddenly reaches the fracture point and breaks.
4. Which of the point is there in a stress strain curve for a ceramic?
a) Ultimate tensile strength
b) Fracture point
c) Limit of proportionality
d) Yield point
Answer: b
Explanation: The correct answer is fracture point. Unlike metals or non metals, ceramics just break which is reach the fracture point after a certain amount of strain.
5. Which of the following is correct?
a) Aluminum oxide reaches fracture point before glass
b) Aluminum oxide reaches fracture point after glass
c) Aluminum oxide reaches fracture point at the same time as glass
d) They do not reach a fracture point
Answer: a
Explanation: Aluminum oxide reaches fracture point before glass. In aluminum oxide for a large amount of stress little strain is produced.
6. Which of the following is correct?
a) Slope of stress strain curve of aluminum oxide is more than glass
b) Slope of stress strain curve of aluminum oxide is less than glass
c) Slope of stress strain curve of aluminum oxide is the same as glass
d) Slope of stress strain curve of aluminum oxide and glass are not comparable
Answer: a
Explanation: The slope of stress strain curve of aluminum oxide is more than glass that is the curve for aluminum oxide is steeper than that of glass.
7. Which of the following can be the tensile strength of aluminum oxide?
a) 600 MPa
b) 800 Mpa
c) 1000 MPa
d) 1200 MPa
Answer: a
Explanation: The range for the tensile strength of aluminum oxide which is a ceramic is 275 MPa – 700 MPa. Therefore only 600 Mpa lies in that range and is the correct answer.
8. Which of the following can be the tensile strength of spinel?
a) 200 MPa
b) 300 Mpa
c) 100 MPa
d) 90 MPa
Answer: a
Explanation: The range for the tensile strength of spinel which is a ceramic is 110 MPa – 245 MPa. Therefore only 200 Mpa lies in that range and is the correct answer.
9. Which of the following can be the tensile strength of fused silica ?
a) 110 MPa
b) 150 Mpa
c) 90 MPa
d) 80 MPa
Answer: a
Explanation: The range for the tensile strength of fused silica which is a ceramic is 110 MPa. Therefore only 110 Mpa is the correct answer.
10. Silicon carbide is ductile.
a) True
b) False
Answer: b
Explanation: Silicon carbide is a ceramic and hence it is not ductile. It does not have the elasticity to be drawn into wire. Any attempts to change its shape will break the ceramic.
This set of Materials Science Multiple Choice Questions & Answers focuses on “Fractures in Ceramics”.
1. Which of the point is there in a stress strain curve for a ceramic?
a) Ultimate tensile strength
b) Fracture point
c) Limit of proportionality
d) Yield point
Answer: b
Explanation: The correct answer is fracture point. Unlike metals or non metals, ceramics just break which is reach the fracture point after a certain amount of strain.
2. Which of the following is correct
a) Aluminum oxide reaches fracture point before glass
b) Aluminum oxide reaches fracture point after glass
c) Aluminum oxide reaches fracture point at the same time as glass
d) They do not reach a fracture point
Answer: a
Explanation: Aluminum oxide reaches fracture point before glass. In aluminum oxide for a large amount of stress little strain is produced.
3. Which of the following is a flexural strength not dependent on?
a) Force
b) Distance between supports
c) Specimen width
d) Length of specimen
Answer: d
Explanation: Flexural strength is dependent on the force applied on the specimen, distance between the supports, width of the specimen and the height of the specimen and hence it does not depend on the length of the specimen.
4. For edge flaws to occur which of the following should be the value of constant in stress intensity factor formula?
a) 1.1
b) 1.2
c) 1.02
d) 1.12
Answer: d
Explanation: The correct answer is 1.12. For an edge flaw to occur, the value of the constant in the stress intensity factor formula should be 1.12.
5. Which of the following can be the tensile strength of fused silica (SiO 2 )?
a) 110 MPa
b) 150 Mpa
c) 90 MPa
d) 80 MPa
Answer: a
Explanation: The range for the tensile strength of fused silica (SiO 2 ) which is a ceramic is 110 MPa. Therefore only 110 Mpa is the correct answer.
6. For zircon for the same flaw size, the intensity factor is more than alumina.
a) True
b) False
Answer: a
Explanation: The above statement is true. For a given flaw size for example 50 micrometers, the intensity factor for zircon is 4.6 units and that of alumina is 3.7 units.
7. The largest constituent elements and flaws increase the flexural strength.
a) True
b) False
Answer: b
Explanation: The above statement is false. The smallest constituent element and flaws increase the flexural strength.
8. Which of the following shows the best fracture strength?
a) Zircon
b) Macor
c) Alumina
d) There fracture strength are not comparable
Answer: a
Explanation: Zircon shows the best fracture strength among the three elements, alumina, zircon and macor.
