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Multiple choice question for engineering

Set 1

1. Plastics and elastomers differ due to their properties of ________
a) Resistivity
b) Dielectric strength
c) Acoustic insulation
d) Extensibility

View Answer

Answer: d [Reason:] Elastomers are polymeric materials similar to plastic resins. They are otherwise known as rubbers. The difference between plastics and elastomers lies in their ability to stretch.

2. Which of the following is not a characteristic of rubber?
a) Non-crystalline
b) Electrical conductivity
c) Chemical resistance
d) Low softening temperature

View Answer

Answer: b [Reason:] Elastomers are hydrocarbon polymeric materials that are non-crystalline in nature. These materials possess high chemical and corrosion resistance, and a relatively low softening temperature. However, they are poor conductors of heat, which in effect make them non-conductors of electricity.

3. Which kind of polymer arrangement does the below diagram represent?
engineering-materials-metallurgy-questions-answers-structure-properties-elastomers-q3
a) Unvulcanized
b) Vulcanized
c) Stretched vulcanized
d) Stretched unvulcanized

View Answer

Answer: c [Reason:] Polymer structures in elastomers are classified as vulcanized (unstretched), unvulcanized, or stretched vulcanized rubber. The vulcanization process involves cross-linking of covalent bonds. This results in a material similar to a thermoset.

4. Which polymeric arrangement does the figure represent?
engineering-materials-metallurgy-questions-answers-structure-properties-elastomers-q4
a) Unvulcanized
b) Vulcanized
c) Stretched vulcanized
d) Stretched unvulcanized

View Answer

Answer: a [Reason:] Polymer structures in elastomers are classified as vulcanized (unstretched), unvulcanized, or stretched vulcanized rubber. In the unstretched state, these elastomers are amorphous. This is due to the arbitrariness of the polymer arrangement.

5. How does crystallinity of an elastomer affect its strength?
a) Increases with increase in crystallinity
b) Increases with decrease in crystallinity
c) Decreases with increase in crystallinity
d) No effect

View Answer

Answer: a [Reason:] When elastomer polymers are stretched, the chains tend to straighten and align. This increases the crystallinity of the elastomer, which in turn increases the strength.

6. The loss of heat in elastomers due to friction is known as ________
a) Resilience
b) Hardness
c) Resistivity
d) Hysteresis

View Answer

Answer: d [Reason:] Resilience is defined as the ability of an elastomer to accumulate energy. Some of this energy is lost due to internal friction or frictional heat. This loss of heat is known as hysteresis.

7. How is the hardness of an elastomer measured?
a) Bloom
b) Brinnell hardness test
c) Rockwell hardness test
d) Shore durometer

View Answer

Answer: d [Reason:] Shore durometer is a standard test conducted to measure the hardness of an elastomer. This scale ranges from values of 0 to 100, indicating a higher hardness for the higher number.

8. What is the thermal conductivity of rubber?
a) 0.04 W/m oC
b) 0.16 W/m oC
c) 0.64 W/m oC
d) 1.12 W/m oC

View Answer

Answer: b [Reason:] Elastomers are regarded as materials having low heat conduction and electrical conduction abilities. They have a low thermal conductivity of 0.16 W/m oC and a specific gravity of 1.0-1.8. The resistivity of elastomers ranges from 106 to 1010 ohm/oC m.

Set 2

1. Teflon is known as the trademark name for ________
a) Tetrafluoride
b) Tetrafluoroethylene
c) Fluorinated ether propane
d) Fluoro ethyl propylene

View Answer

Answer: b [Reason:] Teflon is the trademark name for polytetrafluoroethylene, which is a synthetic fluoropolymer of tetrafluoroethylene (TFE). It can also be called as fluorinated ethylene-propylene (FEP). They are mainly used as coatings due to their ability to reduce friction, wear and tear.

2. Which of the following is not a property of fiberglass?
a) Organic
b) Nonflammable
c) Thermal insulation
d) Reinforcement for plastics

View Answer

Answer: a [Reason:] Fiberglass is known as the glass that has been drawn into fine fibers. They are inorganic in nature which makes them greatly inert. They also exhibit a high strength to weight ratio, non-flammability, and resistance to heat. For engineering applications, they are used for thermal and acoustic insulation, and as reinforcements for plastics.

3. Staple fibers are ______ cm in length.
a) 10 – 14
b) 15 – 38
c) 40 – 55
d) 62 – 80

View Answer

Answer: b [Reason:] Fiberglass is made into either continuous fibers or staple fibers. Continuous fibers can be essentially made into any desired length. Staple fibers, on the other hand, range from 15 – 38 cm.

4. Which chemical composition of fiberglass is used when chemical resistance is not essential?
a) Fused quartz steel
b) Borosilicate
c) Alumina
d) Soda lime

View Answer

Answer: d [Reason:] Depending on the ease of melting and chemical durability, several chemical compositions are compared and chosen to make fiberglass. Fused quartz steel and borosilicate compositions provide the necessary resistance. However, when chemical resistance is not a key requirement, ordinary soda lime is used.

5. The melted glass inserted into a second furnace uses a _______ plate at the bottom.
a) Palladium
b) Aluminum
c) Platinum
d) Copper

View Answer

Answer: c [Reason:] The glass is melted and formed into marbles. These are inserted into a second remelting furnace at a constant rate. This furnace contains a platinum plate at the bottom, holding small orifices from which the required fiber is drawn.

6. The diameter of selected fibers is of the range of _______
a) 0.1 – 0.155
b) 0.01 – 0.1
c) 0.0025 – 0.01
d) 0.00025 – 0.00125

View Answer

Answer: d [Reason:] For any operation, the fibers used are of uniform size. They range from 0.00025 to 0.00125 cm. This size of the fiber depends on the desired properties and intended use of the drawings.

7. Staple fibers differ from continuous fibers due to the use of ________
a) Air blower
b) Manual force
c) Winding tube
d) Lubrication

View Answer

Answer: a [Reason:] Continuous fibers are made from melting process in a two-stage method. Staple fibers are formed by remelting process but differ due to the use of air or steam blower for tractive forces.

8. Which of the following is not a type of glass insulation?
a) Bonded
b) Block
c) Blanket
d) Bore

View Answer

Answer: d [Reason:] Fiberglass is mainly used as an insulating material and as reinforcement. The various types of glass insulations are – bonded, unbounded, block, blanket, and preformed insulation.

9. What is the operating temperature of borosilicate glass?
a) 200-300 F
b) 350-550 F
c) 600-1000 F
d) 1200-1800 F

View Answer

Answer: c [Reason:] Fibrous glass can be used at temperatures even as low as -350 F. The borosilicate type is generally operated at a range of 600 to 1000 F.

10. What is the operating temperature of high silica glass?
a) 300 F
b) 550 F
c) 1250 F
d) 1830 F

View Answer

Answer: d [Reason:] Heat resistance of a fiberglass material depends on the type of glass used. The maximum operating temperature of high silica glass is about 1830 F (1000oC), whereas that of borosilicate glass is 600-1000 F.

11. What is the product obtained when thermosetting resin fiberglass is exposed to heat and pressure?
a) Tetrafluoroethylene
b) Fiberglass reinforced plastic
c) Fiber reinforced fluoroethylene
d) Fiber induced carbon

View Answer

Answer: b [Reason:] Fiberglass reinforced plastic is achieved as a product of fiberglass reinforced in a thermosetting resin and exposed to conditions of heat and pressure. These products were used for military and radar applications. In recent usage, it is being applied to swimming pools and roofing.

Set 3

1. Which of the following is not a result of tempering?
a) Increased ductility
b) Improved toughness
c) Increased electrical conductivity
d) Internal stresses are relieved

View Answer

Answer: c [Reason:] Martensite formed during hardening process is too brittle and lacks toughness and ductility. This makes it unusable for many applications. Therefore, a heat treatment process called tempering is done to bring about these changes.

2. Tempering of martensite steel is done _________
a) Below eutectic temperature
b) Below eutectoid transformation temperature
c) At room temperature
d) At 1000oC

View Answer

Answer: b [Reason:] Tempering is a process of heating martensite steel below the eutectoid transformation temperature (250-650oC). It is held there for some time and slowly cooled to room temperature.

3. Internal stresses in martensite steel are relieved by heating at __________
a) 200oC
b) 500oC
c) 800oC
d) 1000oC

View Answer

Answer: a [Reason:] Tempering usually involves heating the martensite steel below the eutectoid transformation temperature (250-650oC). When this martensite steel is heated at temperatures as low as 200oC, internal stresses are relieved.

4. What kind of transformation occurs during tempering of martensite steel?
a) BCC to FCC
b) BCT to HCP
c) FCC to BCT
d) BCT to α+Fe3C

View Answer

Answer: d [Reason:] Tempering is a process of heating martensite steel below the eutectoid transformation temperature. This heat treatment process transforms martensite (BCT, single phase) into tempered martensite (α+Fe3C) by the diffusional process.

5. How is the tensile strength of the material affected due to tempering?
a) Increases with increase in temperature
b) Decreases with increase in temperature
c) Increases constantly
d) Does not change

View Answer

Answer: b [Reason:] We know that hardness of the material decreases with increase in tempering time. Similarly, the tensile and yield strengths of the material also decrease with increase in tempering temperature.

6. How is the ductility of the material affected due to tempering?
a) Increases with increase in temperature
b) Decreases with increase in temperature
c) Increases constantly
d) Does not change

View Answer

Answer: a [Reason:] The hardness and tensile and yield strengths of the material decrease with increasing tempering temperature. On the other hand, however, it is noted that the ductility of the material increases with an increase in tempering temperature.

7. Low temperature tempering occurs at __________
a) 50-150oC
b) 150-250oC
c) 350-450oC
d) 500-650oC

View Answer

Answer: b [Reason:] Tempering temperature is classified into three classes. Low temperature tempering occurs at 150-250oC. Medium and high temperature tempering occur at 350-450oC and 500-650oC correspondingly.

8. Medium temperature tempering develops a ________ structure.
a) Non-lamellar
b) Sorbite
c) Tempered-troostite
d) Bainite

View Answer

Answer: c [Reason:] Medium temperature tempering is usually carried out in a temperature range between 350oC and 450oC. This process develops a tempered-troostite structure.

9. Tempering that results in a reduction of toughness is known as __________
a) Caustic embrittlement
b) Temper embrittlement
c) End-temper
d) Quench-temper embrittlement

View Answer

Answer: b [Reason:] Tempering of some steels and alloys may result in the reduction of toughness. This phenomenon is known as temper embrittlement.

10. High temperature tempering develops a ________ structure.
a) Non-lamellar
b) Sorbite
c) Tempered-troostite
d) Pearlite

View Answer

Answer: b [Reason:] High-temperature tempering is usually carried out in a temperature range between 500oC and 650oC. This process develops a sorbite structure. This is used to completely eliminate internal stresses in the material.

11. Temper embrittlement occurs at a temperature __________
a) Below 0oC
b) Above 250oC
c) Above 575oC
d) Above 1000oC

View Answer

Answer: c [Reason:] Tempering of some steels and alloys may result in the reduction of toughness. This phenomenon is known as temper embrittlement. Temper embrittlement occurs when the steel is tempered above 575oC which is followed by slow cooling to room temperature.

12. Which tempering process is used to increase the endurance and elastic limit of the material?
a) Low-temperature tempering
b) Medium temperature tempering
c) High-temperature tempering
d) Endurance limit cannot be increased

View Answer

Answer: b [Reason:] Medium temperature tempering is performed between 350oC and 450oC. This process develops a tempered-troostite structure and increases the endurance and elastic limits of the material.

13. What are the applications of medium temperature tempering?
a) Spring and die steels
b) Structural steels
c) Low alloy steels
d) Surface hardened regions

View Answer

Answer: a [Reason:] Medium temperature tempering is applied on materials like spring steels and die steels. Likewise, high-temperature tempering is used on structural steels. Low-temperature tempering is applied to cutting and measuring tools of carbon and low alloy steels, as well as for surface-hardened and case-carburized parts.

Set 4

1. A copolymer of butadiene and acrylonitrile is known as __________
a) Nitrile rubber
b) Butyl rubber
c) Polysulphide rubber
d) Fluorine rubber

View Answer

Answer: a [Reason:] Nitrile rubber is a copolymer formed by a combination of butadiene and acrylonitrile. It has a good tensile strength and exceptional adhesion. It is largely used in aircraft fuel tanks, printing rollers, and O-rings.

2. What is the percentage of elongation of styrene butadiene rubber?
a) 60-70%
b) 140-160%
c) 250-300%
d) 500-600%

View Answer

Answer: d [Reason:] Styrene butadiene rubber is a low-cost synthetic rubber having tremendous resistance to aging. It has a poorer tensile strength which can be improved by vulcanizing, and elongation of 500-600%.

3. Isoprene added to isobutylene gives _______
a) Nitrile rubber
b) Butyl rubber
c) Polychloroprene rubber
d) Silicone rubber

View Answer

Answer: b [Reason:] Butyl rubber is a polymer made from a combination of isobutylene and 3% of isoprene. It possesses low strength and high elongation, with good chemical and dielectric properties. It is mainly used for liners and inner tubes.

4. What is the common name for polysulphide rubber?
a) Neoprene
b) Polyurethane
c) Thiokol
d) Hypalon

View Answer

Answer: c [Reason:] Thiokol is a rubber which holds admirable resistance to oil and solvents. It also has good electrical resistivity and superb resistance to ozone. It is mainly used in aircraft fuel tanks, gaskets et cetera.

5. Which of the following is not a method of fabrication of rubber?
a) Compression molding
b) Calendering
c) Buffing
d) Vacuum forming

View Answer

Answer: c [Reason:] Some of the basic forming and fabrication techniques for rubber include compression molding, calendering, injection and transfer molding, and extrusion among others. Tumbling, trimming, and buffing are techniques of finishing this fabricated rubber.

6. Mica manufactured by internal resistance melting method is melted at ______
a) 1118oC
b) 1208oC
c) 1365oC
d) 1480oC

View Answer

Answer: c [Reason:] Mica is usually manufactured either as ruby mica or phlogopite mica. The synthetic mica is produced by internal resistance melting method. This method uses graphite electrodes and melts mica at 1365oC.

7. Ruby mica is more commonly known as ______
a) Muscovite
b) Phlogopite
c) Urethane
d) Neoprene

View Answer

Answer: a [Reason:] Natural mica is available as muscovite and phlogopite among the commonly used forms. Muscovite, otherwise known as ruby mica, is generally odorless. It is often favored in electrical applications.

8. Natural muscovite is normally stable up to ______
a) 300oC
b) 600oC
c) 800oC
d) 1000oC

View Answer

Answer: b [Reason:] Muscovite contains about 4.5% water and is stable up to 600oC. Above this temperature, it breaks down due to volatilization. Phlogopite contains 3% water and is stable up to 800oC.

9. Which of the following is not a form of mica?
a) Fully trimmed
b) Partially trimmed
c) Film
d) Wire

View Answer

Answer: d [Reason:] Mica is commonly available in four forms classified as fully-trimmed, partially-trimmed, films, or scrap. Fully-trimmed and partially-trimmed mica are of a minimum of 0.007 inches in thickness. This quality of mica influences the cost of the material.

Set 5

1. The response of a material due to the function of heat is known as __________
a) Mechanical property
b) Electrical property
c) Chemical property
d) Thermal property

View Answer

Answer: d [Reason:] Mechanical properties deal with the effects of external forces, while electric properties deal with the effect of the flow of electricity, and chemical properties are related to a material’s effects due to reaction with other substances. Thermal properties deal with heat and temperature effects on the material.

2. The heat capacity of a material defined as ___________
engineering-materials-metallurgy-questions-answers-thermal-properties-q2

View Answer

Answer: a engineering-materials-metallurgy-questions-answers-thermal-properties-q2-exp

3. Specific heat of materials is expressed in terms of __________
a) W/m K
b) J/K
c) J/kg K
d) m3/kg

View Answer

Answer: c [Reason:] Specific heat capacity of a material is an intensive property expressed in terms of J/kg K. Thermal conductivity, heat capacity, and specific volume are expressed in terms of W/m K, J/K, and m3/kg correspondingly.

4. What effect does the addition of thermal energy have on a material?
a) Thermal contraction
b) Thermal expansion
c) No change
d) Reproduction

View Answer

Answer: b [Reason:] Addition of heat or thermal energy results in an increase in magnitude as a theory of basic laws of thermodynamics. Hence, on the addition of thermal energy, thermal expansion occurs.

5. Which term is used to define the temperature at which a substance changes its status from solid to liquid?
a) Boiling point
b) Melting point
c) Condensation point
d) Freezing point

View Answer

Answer: b [Reason:] The temperature at which a substance changes from solid state to liquid is known as the melting point; here the temperatures of solid and liquid are in equilibrium. The shift of liquid state to solid is known as the freezing point. The transition from gaseous state to liquid is known as condensation, while that of liquid to gaseous is known as the boiling point.

6. The melting point of Iron (Fe) is _________
a) 660oC
b) 1084oC
c) 419oC
d) 1538oC

View Answer

Answer: d [Reason:] The melting point of Iron is 1538oC, whereas the melting points of aluminum (Al), zinc (Zn), and copper (Cu) are 660oC, 419oC, and 1084oC in that order.

7. The ability of a body to withstand sudden and severe temperature changes is known as________
a) Thermal shock resistance
b) Thermal resistance
c) Thermal transmittance
d) Deployment

View Answer

Answer: a [Reason:] Thermal shock resistance is the ability of a body to withstand sudden and severe temperature changes. Thermal resistance is a property by which a material resists a heat flow. Thermal transmittance is the rate of transfer of heat through one square meter, divided by the difference in temperature. The thermal admittance is known as the knack of a material to transmit heat when there is temperature variation on its opposite sides.

8. How is the spalling resistance index defined?
engineering-materials-metallurgy-questions-answers-thermal-properties-q8

View Answer

Answer: a engineering-materials-metallurgy-questions-answers-thermal-properties-q8-exp

9. What effect do thermal variations in volume have on a body?
a) Expansion
b) Contraction
c) Cracking
d) Phase transformation

View Answer

Answer: c [Reason:] Cracking is the effect of thermal variation in the volume of a body. Expansion, contraction, and phase transformation are the ways in which these volume changes occur, i.e. they are causes, and not effects.

10. The temperature at which plastics begin to become softer and defer under a load is known as _________
a) Softening point
b) Melting point
c) Eutectic point
d) Heat distortion point

View Answer

Answer: d [Reason:] Heat distortion point is the temperature at which plastics begin to become softer and defer under a load. The softening point is the temperature at which a flat-ended needle of 1 mm2 penetrates the test same at 1 mm2 depth. Eutectic point the temperature at which a mixture freezes or melts. The melting point is the temperature at which the state of the body changes from solid to liquid.