Multiple choice question for engineering
1. Measurement of elevated temperatures is defined as ___________
Answer: b [Reason:] Pyrometry deals with elevated temperatures, generally around 950 F. The apparatus that is used in this process is known as a pyrometer. Thermometry generally deals with the measurement of temperatures below 950 F.
2. What temperature does the dark red color generally deal with?
a) 950 F
b) 1150 F
c) 1175 F
d) 1300 F
Answer: b [Reason:] Temperature of metals can be estimated by simply looking at the color of the hot body. Dark red is assigned a temperature of 1150 F, whereas for faint red, dark cherry, and cherry red it is 950 F, 1175 F, and 1300 F in that order.
3. What temperature is the dark orange color associated with?
a) 1475 F
b) 1650 F
c) 1750 F
d) 1800 F
Answer: b [Reason:] Temperature of metals can be estimated by simply looking at the color of the hot body. Dark orange is associated with a temperature of about 1150 F, while for bright cherry, orange, and yellow it is 1475 F, 1750 F, and 1800 F correspondingly.
4. Bimetallic strips are employed in ________ thermometers.
Answer: c [Reason:] Bimetallic strips made by bonding of high-expansion and low-expansion metals are used in the common thermostat. When used as an industrial temperature indicator, these can be bent into a coil.
5. Bimetallic strips contain _______ as a metal.
a) Muntz metal
b) Yellow brass
Answer: b [Reason:] Bimetallic strips include invar as one metal and yellow brass as another. For higher temperatures, nickel alloy can be used. These can be used in temperatures ranging from -100 F to 1000 F.
6. Why is invar used in bimetallic strips?
a) Low density
b) Low coefficient of expansion
c) High-temperature resistance
d) High abrasion resistance
Answer: b [Reason:] Most bimetallic strips are composed of invar and yellow brass as metal. Invar has the advantage of low coefficient of expansion, whereas yellow brass has the ability to be used at low temperatures.
7. _______ is commonly used in liquid-expansion thermometers.
a) Bourdon tube
b) Spinning rotor gauge
c) McLeod gauge
Answer: a [Reason:] Liquid-expansion thermometers consist of a bulb and an expansible device. The bulb is exposed to the temperature that needs to be measured and usually, a Bourdon tube is used as an expansion device. These are connected by capillary tubing and are filled with a medium.
8. Resistance thermometer generally makes use of ________ for measurement of resistance.
c) Diode bridge
d) Wheatstone bridge
Answer: d [Reason:] Resistance thermometers are based on the principle of increase in electrical resistance with increasing temperature. It consists of a resistance coil mounted in a protecting tube which is connected to a resistance measuring instrument. Generally, Wheatstone bridge is used in this process.
9. Which of these materials is not used for resistance coils?
Answer: c [Reason:] Resistance coils are generally made of nickel, copper, or platinum. Nickel and copper can be used in the temperature range of 150-500 F, whereas platinum can be used between -350 to 1100 F.
10. Liquid expansion thermometers are filled with ________
Answer: a [Reason:] The liquid-expansion thermometer has the entire system filled with an organic liquid or mercury. Mercury is used at a temperature range of -35 to 950 F. Alcohol and creosote are used at -110 to 160 F, and 20 to 400 F respectively.
1. Thermoplastics are formed by ________
a) Addition polymerization
c) Condensation polymerization
Answer: a [Reason:] Thermoplastics are plastic polymer substances formed by addition polymerization process. They are linear polymers containing chain molecules. These plastics tend to become soft when heated and harden when cooled.
2. Which of the following is not a property of thermoplastics?
b) Soft and weak
c) Easy to mold
d) Can be used at high temperatures
Answer: d [Reason:] Thermoplastics tend to become soft when heated due to weak secondary forces and become hard on cooling. This makes it easier to mold them into any required shape any number of times, and therefore makes them recyclable. They are, however, not suitable for use under high temperatures.
3. Which of the following is an example of a thermoplastic?
Answer: c [Reason:] Acetal is an example of engineering thermoplastics. These are the plastics which are typically employed in engineering applications due to high strength, environmental resistance, and physical properties. Other examples of engineering thermoplastics are ethenic, cellulose, polyether etc. Urethane, melamine, and epoxide are examples of engineering thermosetting plastics.
4. Which of the following is not an example of a commodity thermoplastic?
Answer: d [Reason:] Commodity thermoplastics are the most widely used plastics and are available at a lower cost. Phenolic is an example of thermosetting commodity plastic. The remaining choices, along with PVC, are examples of commodity thermoplastics.
5. Which of these is not a type of polyethylene?
a) Low-density polyethylene
b) High-density polyethylene
c) Linear high-density polyethylene
d) Ultra-high molecular weight polyethylene
Answer: c [Reason:] Polyethylene is a plastic made by the polymerization of ethylene (ethene). Based on molecular weight, the method of manufacturing, and density, they are classified into various types. Low-density polyethylene (LDPE), high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), and ultra-high molecular weight polyethylene (UHMWPE) are the four types of polyethylene.
6. To overcome brittleness of polypropylene, ______ is used.
c) Polyvinyl chloride
Answer: a [Reason:] Polypropylene tends to become brittle at low temperatures. Therefore, polyallomer is used to beat this disadvantage. Polyallomer is a block copolymer of polyethylene and polypropylene.
7. Which of the following is not a type of polystyrene?
a) Structural Polystyrene
b) High Impact Polystyrene
c) Styrene Acrylonitrile
d) Acrylonitrile Butadiene Styrene
Answer: a [Reason:] Polystyrene is a plastic polymer made from ethylbenzene. They are brittle, cheap, and are extremely easy to mold. The commonly used polystyrenes are High Impact Polystyrene (HIPS), Acrylonitrile Butadiene Styrene (ABS), and Styrene Acrylonitrile (SAN).
8. ________ is an example of dichloro-ethylene.
a) Plasticized PVC
b) Un-plasticized PVC
c) Chlorinated PVC
d) Polyvinylidene chloride
Answer: c [Reason:] Polyvinyl chloride (PVC) is a polymer made by the polymerization of monomer vinyl chloride. They are low-cost polymers which have good resistance to chemical, oil, electrical attacks. The common forms of PVC are plasticized PVC (PPVC), un-plasticized PVC (UPVC), chlorinated PVC (CPVC), and polyvinylidene chloride (PVDC).
9. Which is the most commonly used fluorocarbon polymer?
Answer: a [Reason:] Polytetrafluoroethylene (PTFE) is regarded as the most common among all fluorocarbon polymers. They possess excellent electrical properties and are chemically inert. PTFE finds application in chemical pipes, valves, non-stick coatings etc.
1. Thermosetting plastics are formed by ________
a) addition polymerization
c) condensation polymerization
Answer: c [Reason:] Thermosetting plastics are formed by condensation polymerization, whereas thermoplastics are plastic polymer substances formed by addition polymerization process. Thermosetting plastics become permanently hard on the application of heat but do not soften on further heating.
2. Which of the following is a property of thermosetting plastics?
a) Can be molded
d) Can be used at high temperatures
Answer: d [Reason:] Thermosetting plastics become permanently hard when they are heated and do not soften on further change. This makes it impossible for them to be molded into different shapes, rendering them unrecyclable. However, they are good to use even at high temperatures.
3. Which among these is an example of a commodity thermosetting plastic polymer material?
Answer: d [Reason:] Commodity thermoplastics are the most widely used plastics and are available at a lower cost. Phenolic, urea, and unsaturated polyesters are common examples of thermosetting commodity plastics. The remaining choices, along with PVC, are examples of the commodity type of thermoplastics.
4. Which of the following is not an example of a thermoplastic polymer?
Answer: d [Reason:] Urethane, Melamine, and Epoxide are common examples of thermosetting engineering plastics. They have higher strength, are more costly, and possess better physical properties than commodity plastics. Acetal is an example of a thermoplastic engineering material.
5. Phenolics are otherwise commonly known as _____
c) Urea formaldehyde
d) Melamine formaldehyde
Answer: a [Reason:] Phenolics are regarded as the oldest type of thermosetting plastics. They are also known as Bakelite. Polyformaldehyde is generally considered as the most important phenolic material.
6. Polyformaldehyde has a good stability up to _____
Answer: c [Reason:] Polyformaldehydes are a combination of phenol and formaldehyde. They are also known as phenol formaldehyde. They are hard and rigid materials and are stable up to 150oC. They also possess good electrical insulation, low thermal conductivity, and are relatively cheap.
7. Melamine formaldehyde can be used at temperatures up to _____
Answer: b [Reason:] Melamine formaldehyde is an amino-formaldehyde material composed of melamine and formaldehyde condensation. They have properties similar to phenolics and urea-formaldehyde. However, they are more resistant to heat and can be used at temperatures up to 95oC.
8. Which plastic material does a combination of dibasic acids and polyhydric alcohols give?
Answer: a [Reason:] Polyester is a thermosetting plastic formed by a reaction of dibasic acids and polyhydric alcohols. They are typically used in safety helmets, machine covers, electrical moldings etc.
9. A polymer having rubber-like properties is known as _______
Answer: c [Reason:] Elastomers are a group of natural and synthetic polymers which have properties similar to that of rubber. They can be stretched up to at least twice their original length and return to their original position, at room temperature. Natural rubber, polyisoprene, butadiene rubber are a few engineering elastomers which as generally used.
10. Which of the following is used as an adhesive?
d) Phenol formaldehyde
Answer: a [Reason:] Epoxides are hard and rigid materials having good dimensional stability. They have good mechanical properties and corrosion resistance. Their typical applications include usage as adhesives, molded parts for electrical and automotive components, sporting items etc.
11. Paraplex is a common trade name for which thermoset?
d) Urea formaldehyde
Answer: b [Reason:] Polyesters are materials having excellent electrical properties, while also being quite cheap. Their common trade names are Selectron, Laminac, and Paraplex. They are used in safety helmets, structural panels, electrical moldings etc.
12. Urea formaldehyde shares properties and applications with which other thermoset?
a) Phenol formaldehyde
d) Melamine formaldehyde
Answer: d [Reason:] Urea and melamine formaldehyde are materials having good hardness, rigidity, and resistance to chemicals. They are both types of amino-formaldehyde materials. Melamine differs from urea formaldehyde due to its heat resistance property, which is higher than that of urea’s.
13. Which of the following is a type of particle-reinforced composites?
d) Sandwich panels
Answer: c [Reason:] Dispersion-strengthened composites are those in which metals and alloys are strengthened by uniform dispersion of the particles of inert material. This, along with large particle composites makes up the types of particle-reinforced composites. Laminates and sandwich panels are two types of structural composites.
14. The below figure represents ______ type of composites.
Answer: b [Reason:] Particle reinforced composites are those in which the particles of similar sizes are combined to reinforce and enhance mechanical properties. Large particle and dispersion-strengthened composites are its two types.
15. Cermet is a _______ composite.
Answer: a [Reason:] A cermet is a composite of metals and ceramics. This falls under the Large Particle type of particle-reinforced composites. This material contains 80-90% of ceramic. These composites are commonly used as cutting tools for hardened steels. A common example of a cermet is cemented carbide.
16. How much volume of carbon black is used in automobile tires?
Answer: c [Reason:] Automobile tires are made of rubber, which is not a high-strength material on its own. Rubber is added with particulate matter such as carbon black to counter this. Around 15 to 30% volume of carbon black is added to the vulcanized rubber.
17. High-temperature strength of nickel alloys can be enhanced using dispersed particles of _______
Answer: a [Reason:] 3% of thoria (ThO) is added as finely dispersed particles to improve the properties of nickel alloys. This material is known as thoria-dispersed (TD) Nickel.
18. SAP composite stands for ______ composite
a) strengthened aluminum powder
b) sintered aluminum powder
c) strengthened ammonium particulate
d) sintered aluminum particulate
Answer: b [Reason:] A SAP (sintered aluminum powder) composite is a type of dispersion-strengthened composite. This composite is strengthened by up to 14% Al2O3 with an aluminum matrix. It is widely used as it retains higher strength and at all temperatures.
19. Which of the following cermet materials is used for rocket motor and jet-engine parts?
a) Tungsten carbide
b) Molybdenum carbide
c) Chromium oxide
d) Titanium bromide
Answer: c [Reason:] Chromium oxide, magnesium oxide, and aluminum oxide are the ceramics belonging to the oxide group of the cermet. They are used for rocket motor and jet-engine parts. Tungsten carbide is used for cutting tools, whereas titanium bromide is used for cutting tool tips. Molybdenum carbide is used in slip gauges and wire-drawing dies.
1. Non-equilibrium phases are shown for their time and transformation using _________
a) Fe-Fe3C diagram
b) TTT diagram
c) CCT diagram
d) TTT and CCT diagram
Answer: d [Reason:] Ferrite, cementite, pearlite, and austenite are equilibrium phases which are based on the iron-iron carbide equilibrium diagram. For other non-equilibrium phases like martensite and bainite, the Fe-Fe3C diagram cannot be used. In such cases, we use the TTT and CCT diagrams.
2. The CCT or the TTT diagrams are used for _________
a) One steel of specific composition
b) A family of various steels
c) Alloy system of various compositions
d) Combination of all alloys and steels with various compositions
Answer: a [Reason:] An individual equilibrium diagram like the Fe-Fe3C can be used to depict an entire alloy system of various compositions. However, a TTT or a CCT diagram can only be used for one steel of a specified composition.
3. What does CCT diagram stand for?
Answer: c [Reason:] Martensite and bainite are non-equilibrium phases which cannot be depicted on a Fe-Fe3C equilibrium diagram. In such cases, either the time-temperature-transformation or the continuous-cooling-transformation diagrams can be used.
4. __________ is used to predict quenching reactions in steels.
a) Isothermal transformation diagram
b) Iron-iron carbide equilibrium diagram
c) Continuous cooling transformation diagram
d) Logarithm scale
Answer: a [Reason:] An isothermal transformation (IT) is a tool used by heat treaters to calculate quenching reactions in steels. The IT diagram can also be called as a time-temperature-transformation diagram.
5. Which of the following is not an alternative name for TTT diagram?
a) S curve
b) C curve
c) Adiabatic curve
d) Bain’s curve
Answer: c [Reason:] Owing to the shape of the diagram, TTT diagrams may be called S curves or C curves. Due to their nature and type of work, they may also be known as isothermal transformation diagrams or Bain’s curves.
6. The first step in constructing a TTT diagram involves _________ the sample.
Answer: d [Reason:] To construct a TTT diagram, a large number of the small specimen are collected and austenised in a furnace. Next, heat treatment and quenching stages are carried out. After each stage, the temperature and time are plotted as curves.
7. Austenising of samples for TTT diagram is done __________ temperature.
a) At room temperature
b) Below melting point
c) Above eutectoid temperature
d) Above boiling temperature
Answer: c [Reason:] A large number of small samples of the same material are collected and austenized in a furnace above the eutectoid temperature. Then it is rapidly cooled at a desired temperature below the eutectoid temperature.
8. Examination of transformation time after quenching is done ___________
a) At room temperature
b) Below melting point
c) Above eutectoid temperature
d) Above boiling temperature
Answer: a [Reason:] Austenising of the sample is done above eutectoid temperature, whereas quenching is done below the eutectoid temperature. After each transformation time, the microstructure is examined at room temperature and plotted in the form of curves.
9. Isothermal transformations of eutectoid steel between 723oC and 550oC produces __________ microstructure.
Answer: a [Reason:] Isothermal transformations of eutectoid steel between 723oC and 550oC bring into being a pearlitic microstructure. The pearlite changes from coarse structure to fine structure as the transformation is decreased in this range.
10. Rapid quenching of eutectoid steel ___________ transforms the austenite into martensite.
a) At room temperature
b) Below 320oC
c) At 550oC
d) Above 723oC
Answer: d [Reason:] An isothermal transformation of eutectoid steel between 723oC and 550oC gives a pearlitic microstructure. Rapid quenching above 723oC transforms the austenitic condition into martensitic condition.
11. Hot-quenching of eutectoid steels in austenitic condition results in formation of ___________
Answer: b [Reason:] If eutectoid steels in austenitic condition are hot-quenched in a 550oC to 250oC range, they are isothermally transformed into bainite. This bainite formed is an intermediate structure between pearlite and martensite.
12. Bainite in iron-carbon alloys has a ___________ structure.
Answer: b [Reason:] Bainite in iron-carbon alloys can be defined as an austenitic decomposition product. It has a non-lamellar eutectoid structure containing α ferrite and cementite (Fe3C).
13. Lower bainite is formed at ___________ temperature range.
Answer: c [Reason:] For eutectoid steels, bainite exists in two forms known as upper and lower bainite. Upper bainite is formed by the isothermal transformation between 550-350oC. Lower bainite is formed between 350-250oC which has much finer cementite particles.
14. Which of the following factors do not affect the critical cooling rate?
a) Chemical composition
b) Hardening temperature
c) Number or nature of grains
d) Purity of steel
Answer: c [Reason:] The slowest rate of cooling of austenite that results in 100% martensite transformation is called critical cooling rate. This depends on the chemical composition, hardening temperature, and metallurgical nature (purity) of steel.
1. Composition up to 0.008% carbon is considered as _________
a) Pure iron
c) Cast iron
d) Annealed steel
Answer: a [Reason:] In general, the different types of ferrous alloys are steel, iron, and cast iron. Pure iron is composed of 0.008% carbon, whereas steel and cast iron contain 0.008-2.0% and over 2% respectively.
2. Steels containing 0.8% C are called ________
d) Mild eutectoid
Answer: a [Reason:] In general, the different types of ferrous alloys are steel, iron, and cast iron. Steels are further subdivided as eutectoid, hypoeutectoid, and hypereutectoid. Eutectoid steels contain 0.8% of carbon content.
3. How much carbon does hypoeutectoid steel contain?
Answer: a [Reason:] In general, the different types of ferrous alloys are steel, iron, and cast iron. Steels are further subdivided as eutectoid, hypoeutectoid, and hypereutectoid. Hypoeutectoid steels contain less than 0.8% of carbon content, whereas hypereutectoid steels contain over 0.8%.
4. Eutectoid steel is heated at __________
Answer: c [Reason:] For the transformation of eutectoid steel, a sample of 0.8% steel is heated at 750oC. It is held at this temperature until a transformation begins.
5. Transformation in eutectoid steels is named as _________
Answer: a [Reason:] For the transformation of eutectoid steel, a sample of 0.8% steel is heated at 750oC and held at that temperature. Due to this, the structure becomes a homogeneous austenite. This process is known as austenitizing.
6. Cooling of hypoeutectoid steel post heating forms __________ ferrite.
c) Hypereutectoid 2.08%
d) Mild eutectoid
Answer: a [Reason:] 0.022-0.8% carbon steel is heated at around 875oC and held at this temperature. This results in the formation of homogeneous austenite. Then the steel is cooled to about 775oC, due to which pro-eutectoid ferrite will nucleate and grow at austenite grain boundaries.
7. Slow cooling of hypereutectoid steel results in formation of __________
a) Proeutectoid cementite
b) Posteutectoid cementite
c) Proeutectoid ferrite
d) Proeutectoid austenite
Answer: a [Reason:] Over 0.8% carbon steel is heated at around 925oC and held at this temperature. This results in the formation of austenite. Then the steel is slowly cooled to form proeutectoid cementite which will nucleate and grow at austenite grain boundaries.
8. A mixture of austenite and cementite is called ___________
Answer: b [Reason:] Slow cooling of eutectic cast iron leads to precipitation of austenite of cementite. This combination of austenite and cementite is called ledeburite. This reaction occurs at 1148oC.
9. Cooling of austenite of eutectoid composition at 723oC results in formation of ________
Answer: c [Reason:] The eutectic reaction of cast iron occurs at 1148oC. Below the eutectic temperature, the cast iron consists of austenite crystals and ledeburite. Cooling of this alloy below 723oC transforms austenite into pearlite.
10. Heating of 4.8% cast iron at _______ results in the formation of liquid metal.
Answer: d [Reason:] If a sample of 4.8% cast iron is heated to about 1450oC for a sufficient time, its structure becomes a homogeneous liquid metal. If this cast iron is slowly cooled, cementite crystals nucleate and grow in the liquid phase.
11. Transformation of hypoeutectic cast iron is applicable for the composition of cast iron of ________ carbon.
d) Over 5%
Answer: a [Reason:] Transformation of hypoeutectic cast iron can be seen for the composition of cast iron between 2.0-4.3%. For eutectic cast iron, this composition is 4.3% carbon, whereas, for hypereutectic cast irons, it is 4.3-5.0% carbon.