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Multiple choice question for engineering

Set 1

1. Which code is followed by the corrosion of metals?
a) Burger’s vector
b) Pilling–Bedworth
c) Frank-Read mechanism
d) Miller’s theorem

View Answer

Answer: b [Reason:] The Pilling-Bedworth ratio is the ratio of the volume of the basic cell of a metal oxide to the volume of the basic cell of an equivalent or standard metal. It is used to find out the likeliness of the metal to corrode or resist it.

2. What is the Faraday’s constant?
a) 96.49 kC mol-1
b) 99.01 kC mol-1
c) 100.3 kC mol-1
d) 104.49 kC mol-1

View Answer

Answer: a [Reason:] The Faraday’s constant is used to determine the magnitude of electric charge per mole of electrons. It is denoted as F and is named after Michael Faraday. The accurate value of this constant is 96485.33289(59) C mol-1.

3. How is the Faraday’s constant defined?
a) F = e NA
b) F = e / NA
c) F = e + NA
d) F = NA / e

View Answer

Answer: a [Reason:] The Faraday’s constant is used to determine the magnitude of electric charge per mole of electrons. It is denoted by F = e NA. Here, e is the charge of an electron and NA is Avogadro’s constant.

4. What is the free energy of formation value for Al2O3?
a) 419 kJ mol-1
b) 1045 kJ mol-1
c) 1576 kJ mol-1
d) 2562 kJ mol-1

View Answer

Answer: c [Reason:] The free energy of formation of metal oxides is denoted by ΔG and is noted at 25oC. This value is 1045 kJ mol-1 for Cr2O3 and 1576 kJ mol-1 for Al2O3.

5. What is the Piling-Bedworth ratio of MgO?
a) 0.41
b) 0.79
c) 1.71
d) 2.03

View Answer

Answer: b [Reason:] The Pilling-Bedworth ratio is the ratio of the volume of the basic cell of a metal oxide to the volume of the basic cell of an equivalent or standard metal. This ratio is 0.41, 0.79, 1.71, and 2.03 for K2O, MgO, Cu2O, and Cr2O3 in that order.

6. The potential of metal in nonstandard conditions is given by _________
engineering-materials-metallurgy-questions-answers-types-corrosion-q6

View Answer

Answer: a [Reason:] Every material has a standard electrode potential that will change based on the purity of the metal. The potential under nonstandard condition is defined by V=V_o-RT/nF ln(M/(M+)).

7. A galvanic cell set up due to differences in concentration of metal ion is known as ________
a) Concentration ion
b) Concentration cell
c) Admiralty ion
d) Admiralty cell

View Answer

Answer: b [Reason:] A region in the electrolyte where the metal ions are less in number is known as anodic. Such differences in concentration of metal ion may result in the formation of a galvanic cell known as concentration cell.

8. A galvanic cell formed due to residual stresses is known as ________
a) Stress cell
b) Residual cell
c) Residual ion
d) Admiralty cell

View Answer

Answer: a [Reason:] A galvanic cell can be formed due to various residual stresses in a metal. The stressed region is more active and anodic in nature. These cells can be formed due to dislocation density in a cold worked metal or in a polycrystalline metal.

9. The phenomenon where the density of a metal is exceptionally low due to increasing potential is known as _______
a) Polarization
b) Ionization
c) Passivation
d) Canonization

View Answer

Answer: c [Reason:] When the potential of metal increases, its current density increases. However, after the critical value, it is lowered suddenly and remains constant for a while. This is known as passivation.

Set 2

1. How is fracture stress defined?
a) MN m-2
b) J m-2
c) mm
d) GN m-1

View Answer

Answer: a [Reason:] Fracture is defined as the breaking of a material into multiple parts. The fracture stress is defined as meganewton per square meter or MN m-2 and is denoted by σf.

2. What is the SI unit of fracture toughness?
a) N m-2
b) J m-2
c) J m-1
d) N m-1

View Answer

Answer: b [Reason:] Fracture toughness is regarded as the rate of strain energy released. Its SI unit is joule per meter square (J m-2) and is denoted as Gc.

3. The tensile strength required to break interatomic bonds across two adjacent planes is ________
a) Y
b) Y/2
c) Y/4
d) Y/6

View Answer

Answer: d [Reason:] Calculations for shear strength of perfect crystal has been found to be similar to that of two adjacent planes. It was determined that the tensile strength necessary to rupture interatomic bonds of two adjacent atomic planes is of the order of Y/6.

4. What is the breaking stress of brittle materials?
a) Y/6
b) Y/10
c) Y/100
d) Y/1000

View Answer

Answer: d [Reason:] It was found that the tensile strength of two adjacent atomic planes was Y/6. However, brittle materials may break at a stress of the order of Y/1000. Here, Y is the Young’s modulus.

5. In crystalline materials, fracture occurs normal to crystallographic planes called ___________
a) Fracture point
b) Cleavage plane
c) Brittle plane
d) Crystallographic point

View Answer

Answer: b [Reason:] In crystalline materials, fracture usually occurs after some deformation. In these materials, the fracture occurs normal to crystallographic planes called cleavage planes.

6. What is the surface energy of a crack?
a) ϒ
b) 2 ϒ c
c) 4 ϒ c
d) 12 ϒ c

View Answer

Answer: c [Reason:] Griffith suggested the norm for the formation and spreading of cracks in brittle materials. He found that the surface energy of the crack is 4 ϒ c. Here, ϒ is the surface energy per unit area of the material.

7. The maximum stress at the tip of the crack is defined by _________
engineering-materials-metallurgy-questions-answers-ductile-brittle-fracture-q7

View Answer

Answer: c [Reason:] When tensile stress is applied to a material, the maximum stress occurs at the tips. This maximum stress is denoted as σmax and is given by engineering-materials-metallurgy-questions-answers-ductile-brittle-fracture-q7-a .

8. Griffith theory is applicable for ______ materials
a) All brittle
b) Perfect brittle
c) All ductile
d) Perfect ductile

View Answer

Answer: b [Reason:] The stress required to cause brittle fracture varies inversely as the square root of crack length. From observation, we understand that Griffith theory is applicable only to perfect brittle materials like glass.

Set 3

1. How much SiO2 does Pyrex contain?
a) 70.3%
b) 73%
c) 80.5%
d) 91%

View Answer

Answer: c [Reason:] Pyrex is a borosilicate glass having a low thermal expansion. It consists of 80.5% SiO2 along with B2O3 (11.9%), and small quantities of Na2O, K2O, CaO, and Al2O3. This glass is mainly used in laboratory equipment and kitchenware.

2. How does the addition of magnesia and alumina affect soda lime glass?
a) Enhances mechanical strength
b) Reduces porosity
c) Increases softening temperature
d) Improves chemical durability

View Answer

Answer: d [Reason:] Sodium carbonate is added to fused quartz glass to lower glass transition temperature. However, this results in water solubility. In order to prevent this, magnesia (MgO) and alumina (Al2O3) are added, which increases chemical durability of the glass.

3. What is the melting temperature of fused quartz?
a) 1112oC
b) 1328oC
c) 1525oC
d) 1723oC

View Answer

Answer: d [Reason:] Fused quartz is a glass made of chemically-pure silica. It has tremendous resistance to thermal shock and has a melting temperature of about 1723oC. However, it has a low thermal expansion and is generally hard.

4. What is the maximum usable temperature of soda like glass?
a) 860 F
b) 941 F
c) 1084 F
d) 1324 F

View Answer

Answer: a [Reason:] Soda lime glass is regarded as the most preferred form of glass due to its low cost and ease of use. Annealed glass can be used up to 860 F whereas tempered form may be usable up to 480 F. These glasses are used in ordinary windows and bottles.

5. What is the Kovar type of glass?
a) Low expansion type
b) Low electrical loss type
c) Sealing type
d) Ultraviolet transmitting type

View Answer

Answer: c [Reason:] Kovar glass is a well-known type of sealing grade of borosilicate glass. These are used in glass-to-metal sealing applications.

6. What is the crown type of glasses?
a) Laboratory apparatus grade
b) Optical grade
c) Sealing type
d) Ultraviolet transmitting type

View Answer

Answer: b [Reason:] Optical grade is one brand of borosilicate glass illustrated by high light transmission (HLT). They also possess good corrosion resistance. The optical grade of glass is otherwise known as the crown.

7. What are lead glasses used for?
a) Kitchenware
b) Optical components
c) Electronic tubes
d) Temperature thermometers

View Answer

Answer: b [Reason:] Lead glasses are known as lead-alkali glasses which contain lead as its primary constituent. They have high electrical resistivity and are moderately economical. These glasses are used in optical applications, neon-sign tubing, and electrical bulb stems.

8. Which type of glass is regarded as the most heat resistant?
a) Fused silica
b) Aluminosilicate
c) 96% silica
d) Borosilicate

View Answer

Answer: a [Reason:] Fused silica is characterized as 100% silicon dioxide and is known as fused quartz in its naturally occurring state. It has a high level of transparency owing to its purity. This glass is heat resistant up to 1650 F in continuous service, and up to 4172 F in short-term service, making it the most heat-resistant glass.

9. What is 96% silica glass used for?
a) Heat shield
b) Combustion tubes
c) Electronic tubes
d) Temperature thermometers

View Answer

Answer: a [Reason:] Ninety-six-percent silica glasses are similar to fused silica, but are easier to fabricate and have a higher coefficient of expansion. These can be used as heat shields in space vehicles and other chemical glassware. Aluminosilicate glasses can be used in high-temperature thermometers and combustion tubes.

10. What is the maximum service temperature of aluminosilicate glass?
a) 220oC
b) 460oC
c) 650oC
d) 1200oC

View Answer

Answer: c [Reason:] Aluminosilicate glasses are generally expensive and have more thermal shock resistance. Their maximum service temperature in the annealed state is 650oC. The maximum service temperatures for soda lime and fused silica are 460oC and 1200oC correspondingly.

Set 4

1. What is the trade name for natural polyisoprene?
a) Natural rubber
b) Neoprene
c) Silicone
d) Buna acrylonitrile

View Answer

Answer: a [Reason:] Natural rubber is a common material consisting of isoprene combined with impurities and water. Natural rubber is also known as India rubber and belongs to natural polyisoprene chemical group.

2. What is the percentage of elongation of styrene butadiene?
a) 450-500%
b) 400-600%
c) 500-700%
d) 800%

View Answer

Answer: a [Reason:] Styrene butadiene refers to a high abrasion resistant rubber composed of styrene and butadiene. These rubbers go by the common name of Buna S or SBR (styrene butadiene rubber). The percentage of elongation of SBR is 450-500%.

3. What is Buna N rubber?
a) Styrene-butadiene
b) Chloroprene
c) Polyisoprene
d) Acrylonitrile butadiene

View Answer

Answer: d [Reason:] Buna N is a synthetic rubber composed of acrylonitrile and butadiene. It is also commonly known as NBR, Krynac, or Europrene. This rubber is used in O-rings and hoses.

4. What is the service temperature of polysiloxane?
a) -50 to 150
b) -50 to 105
c) -60 to 120
d) -90 to 250

View Answer

Answer: d [Reason:] Polysiloxane, otherwise known as silicone (SIL) is a rubber used for its temperature insulation properties. It has a 600% elongation and is most useful around a temperature range of -90oC to 250oC.

5. What is the hardening temperature of unvulcanized natural rubber?
a) 5oC
b) 30oC
c) 105oC
d) 150oC

View Answer

Answer: a [Reason:] Unvulcanized natural rubber is a tough and elastic material which softens of heating. It becomes tacky at 30oC and hardens at around 5oC. This rubber oxidizes to a sticky mass when out in the sun.

6. Which of the following is not a characteristic of natural rubber?
a) Cheap
b) High strength
c) High hysteresis
d) Abrasion and tear resistant

View Answer

Answer: c [Reason:] Natural rubber is processed from a liquid known as rubber latex. It has high strength and possesses good tear and abrasion resistance. However, it is easily attacked by solvents and gasoline, and also possesses low hysteresis.

7. Addition of ______ results in the vulcanization of rubber.
a) Nitrogen
b) Sulfur
c) Carbon monoxide
d) Particulate matter

View Answer

Answer: b [Reason:] Vulcanization is a process which increases the strength of natural rubber. It is carried out by heating a mixture of raw rubber and sulfur. The vulcanized rubber is commonly used in the manufacture of tires.

8. __________ is a reinforcement filler.
a) Carbon black
b) Chinaclay
c) Barium sulfate
d) Chalk

View Answer

Answer: a [Reason:] Fillers can be classified as either reinforcing fillers or inactive fillers. Carbon black and synthetic white fibers based on silica and alumina are examples of reinforcing fillers. Talc, barium sulfate, chalk, and chinaclay are examples or inactive fillers.

9. Buna S rubbers consisting of over 50% styrene are considered as _________
a) Polymer
b) Plastic
c) Fibers
d) Whisker

View Answer

Answer: b [Reason:] Buna S (SBR) rubbers differ and quality and grades with respect to the amount of styrene and butadiene. Low-temperature resistant rubber may only contain 9% styrene whereas 44% styrene has good flow characteristics. When the amount of styrene exceeds 50%, it is considered plastic.

10. What is ACM elastomer?
a) Isobutylene Isoprene
b) Ethylene propylene
c) Polyacrylate
d) Polybutadiene

View Answer

Answer: c [Reason:] Polyacrylate elastomers, also known as acrylics, are composed of polymers of butyl or ethyl acrylate. These elastomers are used for special purposes with a low-volume usage, such as parts involving oil.

11. What is the glass transition temperature of polybutadiene?
a) -100 F
b) -25 F
c) 125 F
d) 300 F

View Answer

Answer: a [Reason:] Polybutadiene elastomers are known for their low-temperature performance. They have the lowest brittle or glass transition temperature after silicones. These elastomers possess excellent resilience and abrasion resistance.

12. What is Hypalon?
a) Polysulphide
b) Urethane
c) Chlorosulfonyl polyethylene
d) Isobutylene Isoprene

View Answer

Answer: c [Reason:] Chlorosulfonyl polyethylene is a special elastomer used in a combination with another elastomer or by itself. It is otherwise known as Hypalon or CSM. A polysulphide elastomer is otherwise known as Thiokol.

Set 5

1. Lead is a metallic crystal having a _______ structure.
a) FCC
b) BCC
c) HCP
d) TCP

View Answer

Answer: a [Reason:] Crystalline solids are classified as either metallic or non-metallic. Pb, along with Cu, Ag, Al, and Ni, has a face-centered cubic structure.

2. Which of the following has HCP crystal structure?
a) W
b) Mo
c) Cr
d) Zr

View Answer

Answer: d [Reason:] Crystalline solids are classified as either metallic or non-metallic. W, Mo, and Cr are examples of the body-centered cubic structure of crystals. The HCP structure is found in Mg, Zn, Ti, Cd, Zr, and others.

3. Amorphous solids have _______ structure.
a) Regular
b) Linear
c) Irregular
d) Dendritic

View Answer

Answer: c [Reason:] Materials in which the molecule is the basic structural solid and has an irregular structure is known as amorphous solid. Crystalline solids, on the other hand, usually are arranged in a regular manner.

4. At ________, iron changes its BCC structure to FCC.
a) 308oC
b) 568oC
c) 771oC
d) 906oC

View Answer

Answer: d [Reason:] Similar to metallic crystals, a few non-metallic crystals also change form due to temperature and pressure differences. This process is termed as polymorphism. Iron changes from BCC at room temperature to FCC form at 906oC.

5. At room temperature, tin is formed into _________
a) Gray tin
b) White tin
c) Red tin
d) Yellow tin

View Answer

Answer: b [Reason:] Similar to metallic crystals, a few non-metallic crystals also change form due to temperature and pressure differences. Tin crystallizes in a non-metallic diamond structure (gray tin) at low temperatures. At room temperature, it forms a metallic structure (white tin).

6. Which of the following is a property of non-metallic crystals?
a) Highly ductile
b) Less brittle
c) Low electrical conductivity
d) FCC structure

View Answer

Answer: c [Reason:] Non-metallic crystals are less ductile and have low electrical conductivity. On the other hand, metallic crystals are differing since they are more ductile and have high electrical conductivity.

7. Which of the following is not an amorphous material?
a) Glass
b) Plastics
c) Lead
d) Rubbers

View Answer

Answer: c [Reason:] Materials in which the molecule is the basic structural solid and has an irregular structure are known as amorphous solid. Most amorphous materials are polymers such as plastics and rubbers. The most common amorphous material is glass.

8. The crystal lattice has a _________ arrangement.
a) One-dimensional
b) Two-dimensional
c) Three-dimensional
d) Four-dimensional

View Answer

Answer: c [Reason:] Lattice is defined as the regular geometrical arrangement of points in a crystal space. Space or crystal lattice is a three-dimensional network of imaginary lines connecting the atoms.

9. The smallest portion of the lattice is known as __________
a) Lattice structure
b) Lattice point
c) Bravais crystal
d) Unit cell

View Answer

Answer: d [Reason:] Lattice is defined as the regular geometrical arrangement of points in a crystal space. The unit cell is the smallest portion of the lattice, which when repeated in all directions gives rise to a lattice structure.

10. Bravais lattice consists of __________ space lattices.
a) Eleven
b) Twelve
c) Thirteen
d) Fourteen

View Answer

Answer: d [Reason:] There are fourteen ways in which points can be arranged in a space so that each has identical surroundings. These fourteen space lattices constitute the Bravais space lattices.

11. A unit cell that contains lattice points only at the corners is known as _________
a) Primitive unit cell
b) Secondary unit cell
c) Layered unit cell
d) Derived unit cell

View Answer

Answer: a [Reason:] If a unit cell chosen contains lattice points only at its corners, it is called a primitive or simple unit cell. It contains only one lattice point since each point at the eight corners is shared equally with adjacent unit cells.

12. The axial relationship of a monoclinic crystal system is given as ___________
a) a = b = c
b) a = b ≠ c
c) a ≠ b = c
d) a ≠ b ≠ c

View Answer

Answer: d [Reason:] The crystal system is a format by which crystal structures are classified. Each crystal system is defined by the relationship between edge lengths a, b, and c. For monoclinic, orthorhombic, and triclinic systems, the axial relationship is given by a ≠ b ≠ c.

13. The axial relationship of a rhombohedral crystal system is given as ___________
a) a = b = c
b) a = b ≠ c
c) a ≠ b = c
d) a ≠ b ≠ c

View Answer

Answer: a [Reason:] The crystal system is a format by which crystal structures are classified. Each crystal system is defined by the relationship between edge lengths a, b, and c. For cubic and rhombohedral systems, the axial relationship is given by a = b = c.

14. The interracial angles of a hexagonal crystal system are given by __________
a) α = β = ϒ = 90o
b) α = β = 90o ϒ = 120o
c) α = β = ϒ ≠ 90o
d) α ≠ β ≠ ϒ ≠ 90o

View Answer

Answer: b [Reason:] The crystal system is a system by which crystal structures are classified. Each crystal system is defined by the relationship between edge lengths a, b, and c and interaxial angles α, β, and ϒ. For hexagonal system, the interaxial angles are given by α = β = 90o ϒ = 120o.

15. The interracial angles of a triclinic crystal system are given by __________
a) α = β = ϒ = 90o
b) α = β = 90o ϒ = 120o
c) α = β = ϒ ≠ 90o
d) α ≠ β ≠ ϒ ≠ 90o

View Answer

Answer: d [Reason:] The crystal system is a system by which crystal structures are classified. Each crystal system is defined by the relationship between edge lengths a, b, and c and interaxial angles α, β, and ϒ. For the triclinic system, the interaxial angles are given by α ≠ β ≠ ϒ ≠ 90o.

16. What is the atomic radius of a BCC crystal structure?
a) a/2
b) a/4
c) a√2/4
d) a√3/4

View Answer

Answer: d [Reason:] Atomic radius is defined as half the distance betwrrn the centers of two neighbouring atoms. The atomic radius of a simple cube and HCP is a/2 respectively, whereas it is a√2/4 and a√3/4 for FCC and BCC respectively.

17. What is the coordination number of a simple cubic structure?
a) 6
b) 8
c) 10
d) 12

View Answer

Answer: a [Reason:] Coordination number is defined as the number of nearest neighboring atoms in crystals. The coordination number for simple cubic structure is 6, whereas it is 8 and 12 for BCC and FCC respectively.

18. What is the atomic packing factor of BCC structure?
a) 0.54
b) 0.68
c) 0.74
d) 0.96

View Answer

Answer: b [Reason:] The density of packing in a crystal is determined using the atomic packing factor (APF). The APF of FCC and HCP structures is 0.74, and 0.54 for simple cubic structure, whereas it is 0.68 for BCC structure.