Multiple choice question for engineering
1. How much carbon is present in cast irons?
a) Less than 0.05%
b) Up to 1.5%
c) 1.5% to 2%
d) More than 2%
Answer: d [Reason:] Cast Irons are ferrous alloys containing more than 2% of carbon, along with silicon, sulphur, manganese, and phosphorus. Maraging steels contain less than 0.05% carbon, while plain carbon steels contain up to 1.5% carbon.
2. Cast iron is a _____ alloy.
Answer: a [Reason:] Cast irons are eutectic alloys made of iron and carbon. Since iron is available in abundance, they are easy to find and are less expensive. Therefore cast irons are the cheapest of all metals.
3. Iron obtained from broken ______ is known as white iron.
Answer: a [Reason:] Upon, cementite becomes a silvery-white compound. This is due to the brittle nature of cementite. This fracture results in white cast iron.
4. If the iron surface contains graphite, it is known as ________
a) Alloy cast iron
b) White iron
c) Grey iron
d) Spheroidal graphite
Answer: c [Reason:] When an iron containing graphite is fractured, the surface becomes grey. This is due to the presence of graphite flakes in the iron structure. Hence, it is known as grey iron.
5. Which element causes cementite to behave in a stable manner?
Answer: b [Reason:] Sulphur has a stabilizing effect in cementite. This helps it easily break the cementite and produce white iron.
6. An iron with high-silicon content is a _______
a) White iron
b) Grey iron
c) Malleable iron
d) Pig iron
Answer: b [Reason:] Silicon causes cementite to behave in an unstable manner, which decomposes and releases graphite. If there is a high-silicon presence, more graphite is released and makes it a grey iron. If low-silicon is available, then it becomes a white iron.
7. What is the effect of phosphorus and sulphur in cast irons?
a) Induces brittleness
b) Increases strength
c) Destabilizes cementite
d) No effect
Answer: a [Reason:] Although sulphur stabilizes cementite, it causes brittleness. The same is true for phosphorus, due to which both elements are limited to a minimum quantity. Manganese is used to increase the strength of an iron, which also controls the harmful effects of sulphur.
8. Decomposition of cementite to form ferrite and graphite is known as _______
a) Decomposition of cast irons
b) Production of cast irons
c) Growth of cast irons
d) Prevention of growth of cast irons
Answer: c [Reason:] When cementite is heated at 700C it decomposes into ferrite and graphite. This causes it to occupy more space than the original structure. This phenomenon is known as the growth of cast irons.
9. Which of these are applications of grey cast iron?
a) Camshafts, engine blocks
b) Wear plates, pump linings
c) Brake shoes, pedals
d) Gears, rocker arms
Answer: a [Reason:] Grey cast irons have good strength and corrosion resistance. Therefore, they are used in camshafts and engine blocks. White cast irons are used for pump linings, whereas malleable cast iron is used for pedals and levers. Spheroidal graphite is used in gears and rocker arms.
10. Which of the following cast irons cannot be machined?
a) White cast iron
b) Grey cast iron
c) Malleable cast iron
d) Spheroidal graphite cast iron
Answer: a [Reason:] White cast irons are used where hardness and wear resistance matter, like grinding and crushing. Since it is hard, it cannot be machined. Grey and malleable cast irons, on the other hand, have excellent machinability. Spheroidal graphite cast irons also possess good machinability.
11. How are malleable cast irons designated for different grades?
a) By tensile strength
b) By six or seven-digit numbers
c) By five-digit numbers
d) By alphabets
Answer: c [Reason:] ASTM has designated the grading system for malleable cast irons in five-digit numbers. A grade 32510 has a yield strength of 32500 psi. Six or seven-digit numbers are used to designate spheroidal graphite cast irons (60-40-18 with ferritic structure). Grey cast irons are designated by their tensile strength (grade 20 denotes a tensile strength of 20000 psi).
12. What is the effect of Nickel on cast irons?
a) Stabilizes carbides
b) Increases hardness
c) Refines grain structure
d) Improves corrosion resistance
Answer: c [Reason:] Addition of nickel in cast irons refines the grain structure, and has a graphitizing effect on cementite. Molybdenum and Vanadium are used to increase the hardness of cast irons, while Chromium stabilizes carbides. Copper improves the resistance to corrosion.
13. What is the defining property of Wrought Irons?
a) High carbon
b) Low carbon
c) No carbon
d) Completely carbon-filled
Answer: b [Reason:] Wrought irons are iron alloys contain a very low amount of carbon (less than 0.08%). They were used for producing nails, chains, and bolts initially, but aren’t used these days.
1. Phenolic resin and fine dry silica are mixed with ________ for shell mold casting.
a) Warm water
b) Cold water
Answer: d [Reason:] The mold material of shell mold casting contains 5-10% phenolic resin mixed with fine dry silica. These are mixed with either dry oil or in the presence of alcohol. This pattern is heated to about 230-600oC.
2. In shell molding, the pattern and sand are inverted after _________
a) 20-30 seconds
b) 1-2 minutes
c) 45-50 minutes
d) 3-4 hours
Answer: a [Reason:] The pattern made in shell mold casting is heated to about 230-600oC. Then the sand-resin mixture is blown over its surface. The heated pattern melts and gardens the resins. After a specified time of 20-30 seconds, the pattern and sand are inverted, which gives a normal shell thickness of 6 mm.
3. The molten wax in investment casting is at a pressure of _______
a) 1 bar
b) 4 bar
c) 12 bar
d) 26 bar
Answer: b [Reason:] In investment casting, wax or plastic is injected under pressure into the die as the pattern is used to make a die out of soft material. The molten wax is slightly above its melting point and injection pressure is above 4 bar. If it is a plastic material like polystyrene, the injection pressure may be of the order of 35 bar with higher temperature.
4. Which of these is a refractory powder used in ceramic mold casting?
Answer: c [Reason:] In ceramic mold casting, the ceramic slurry is prepared by mixing fine-grained refractory powders. These powders are Zircon, alumina, fused silica, and patented bending agents. The slurry is applied to the pattern surfaces and baked in a less expensive fireclay.
5. Lost wax process is used for making items of ___________
a) Brass and bronze
Answer: a [Reason:] Investment casting method is also known as lost wax method. This method is used to make brass and bronze statues of religious images, jewelry, and dentistry. The molten metal is poured into an already made mold cavity by melting the mold pattern in the mold itself.
6. Permanent mold casting is otherwise known as _____________
a) Pressure die casting
b) Gravity die casting
c) Centrifugal casting
d) Continuous casting
Answer: b [Reason:] In gravity die casting, the mold is generally made of two halves hinged at one end. This method is useful for making simple components with uniform wall thickness. This process is otherwise also known as permanent mold casting.
7. Centrifugal casting is used for making _________
a) Solid casting
c) Washing machine parts
d) Hollow casting
Answer: d [Reason:] Centrifugal casting is used for making hollow castings like a pipe without using core. The end of the mold is closed by end cores to prevent the flow of metal. The metal is poured through a long spout and rotated by an electric motor or by mechanical means.
8. How can cracks in casting be avoided?
a) Soft ramming
b) Correct pouring temperature
c) Tapered edges
d) Correct gating system
Answer: c [Reason:] Cracks in castings occur due to the presence of sharp edges. When these edges are tapered, cracks can be minimized. Ramming, pouring temperature, and gating systems are checked for other kinds of defects.
1. Which of the following is a glass forming technique?
a) Powder pressing
b) Hydro-plastic forming
c) Slip casting
d) Fiber forming
Answer: d [Reason:] Glass forming is done by heating the raw materials to elevated temperatures. The common glass forming techniques are Pressing, Blowing, Drawing, and Fiber forming. Glass forming operation does not require drying and firing of the materials.
2. Drawing and firing operations are done on which of these processes?
b) Fiber forming
d) Slip casting
Answer: d [Reason:] Slip casting, along with hydro-plastic forming and powder pressing, is a particulate forming process of ceramic fabrication. All the processes of particulate forming undergo drying and firing operations. Drying process removes the liquid, whereas firing improves its density and strength.
3. Which of the following is not a form of powder pressing?
a) Hot pressing
b) Cold pressing
Answer: b [Reason:] Powder pressing is a ceramic formation technique used to fabricate both clay and non-clay compositions. A powdered substance is added with water and pressure is applied in this process. Uniaxial, Isostatic (hydrostatic), and hot pressing are the three types of powder pressing operations.
4. What is the firing temperature for particulate forming processes?
Answer: d [Reason:] Firing is a process carried out to improve the strength and density of a part, under the application of high temperature. This is generally carried out after the drying process. After drying, the body is fired at a temperature of 900oC to 1400oC. This temperature depends on the composition and properties of the component.
5. What does the term ‘green’ refer to for drying and firing operations?
a) Fired but not dried
b) Dried but not fired
c) Dried then fired
d) Fired then dried
Answer: b [Reason:] Drying and firing are two operations carried out in a particulate forming technique of ceramic fabrication. Usually, the body is dried before it is fired. In some cases, however, the body may be formed and dried but not fired. Such a body is referred to as ‘green’.
6. Which pressing technique employs a rubber envelope and application of pressure by fluid?
a) Hot pressing
b) Uniaxial pressing
c) Isostatic pressing
d) Powder pressing
Answer: c [Reason:] Hot, uniaxial, and isostatic pressing are techniques of the powder pressing method. In the isostatic method, a rubber envelope contains the powdered material which is applied pressure on by a fluid, equally in all directions. This differs from uniaxial pressing as the pressure is only applied in a single direction for that operation, but is similar in the sense that they both require being fired after pressing.
7. Which of these holds true for cementitious bonds?
a) High cost
b) Easy to repair
c) Short curing time
d) Hard to repair
Answer: b [Reason:] Cementitious bonds are advantageous as the molds and equipment are available are a low cost and that they are easy to patch and repair. One of the disadvantages of these is that large castings require a long time for curing.
8. Injection molding can be used for parts of thickness up to __________
a) 4 mm
b) 6 mm
c) 8 mm
d) 12 mm
Answer: b [Reason:] Injection molding forms thin, long, and twisted shapes with good reproducibility. They cannot, however, be used for parts whose thickness is more than 6 mm. Another major disadvantage of injection molding is that the cost of molds is generally high.
9. What is the common name for fired clay wares?
Answer: c [Reason:] Pottery is defined as the generic name for all fired clay ware, where clay is referred to as a ceramic. This has even been defined by the American Society of Testing Materials. These days, however, this term has been often associated with being colored and porous.
10. The shape forming process PIM known as __________
a) Porcelain Injection Molding
b) Plastic Injection Molding
c) Particulate Injection Molding
d) Pottery Injection Molding
Answer: a [Reason:] Porcelain Injection Molding is a shape forming process employed for fabrication of tableware. It is generally used for mass production of parts of intricate shapes. However, this is not a very common method of pottery.
11. What is the firing temperature of structural clay products?
Answer: d [Reason:] Clay products are cut into wires after undergoing the process of crushing, disintegration, and extrusion. They are then dried and fired at a temperature of 980-1095oC. This depends on the maturing temperature of the clay.
12. Which of the following is a property of porcelain?
Answer: c [Reason:] Porcelain is a glazed or unglazed type of whiteware ceramic. They are vitreous in nature (hard and nonabsorbent). They are usually used for their mechanical, electrical, chemical, and thermal properties. Unlike china, it requires only a single firing operation due to which it is cheaper.
13. What is china commonly used for?
a) Electrical insulators
c) Laboratory equipment
Answer: b [Reason:] China is glazed or unglazed vitreous whiteware ceramic used for nontechnical purposes. They are mainly used as dinnerware and artworks as they are available in more colors due to a lower maturing temperature. Porcelain is used for electrical insulators and laboratory equipment.
14. Salt glazing is a manufacturing technique of _______ ceramics.
a) structural clay
Answer: a [Reason:] Salt glazing is a technique of fabrication of structural clay products. The salt is added after the firing process to add a vitreous coating. This is generally used on structural tiles and conduit.
1. Which of the following is a property of ceramics?
a) Low strength
b) Low melting point
c) Resistant to corrosion
d) Bad insulation
Answer: c [Reason:] Ceramics are nonmetallic, inorganic solids which are used at high temperatures and therefore have a high melting point. They are good thermal and electrical insulators and possess good resistance to oxidation and corrosion. They are also strong, hard, and brittle.
2. Porcelain is a type of ______ ceramic.
Answer: a [Reason:] Whiteware is a type of ceramic product which contains porcelain, stoneware, china, pottery etc. It is not necessarily white but contains mostly clay, feldspar, and whiting. It finds application is tableware, wall tiles, sanitary ware etc.
3. Diamond and corundum are examples of _____ ceramics.
Answer: d [Reason:] Abrasives are a kind of ceramic materials which are used for making grinding wheels, abrasive cloth and paper. Diamond, carborundum, and corundum are common abrasive materials.
4. Which of the following is not a step in making ceramics?
a) Powder pressing
Answer: c [Reason:] Ceramics are made by pressing a powder into a compact, and then sintering. Some other ceramics are made by gluing the powders together, which is known as vitrification. Some compounds have metallic properties, but they are not alloys.
5. Which material is commonly used in electronic devices?
Answer: d [Reason:] Germanium (Ge) is a metalloid element frequently used in electronic devices. Silicon (Si) is also known to be used in semiconductors and other devices. Alumina is used as an electrical insulator, while Titania and Silica are used as pigment and abrasives respectively.
6. Which of the following carbides are used for cutting tools?
a) Silicon carbide
b) Tungsten carbide
c) Vanadium carbide
d) Chromium carbide
Answer: b [Reason:] Tungsten carbide (WC) belongs to the carbide class of engineering ceramics. It is used for cutting tools. Silicon carbide and boron carbide are used as abrasive, whereas vanadium carbide and tantalum carbide are used as wear-resistant materials. Chromium carbide is used as wear coating.
7. Which class of engineering ceramics generally includes lubricant materials?
Answer: a [Reason:] Molybdenum disulfide (MoS2) and tungsten disulfide (WS2) are common sulfide materials used in lubrication. Metalloid elements like germanium and silicon are used as electronic devices. Intermetallics like Nickel aluminide are used in water coatings.
8. Which of the following is a characteristic of alumina?
a) Excellent hardness
b) Good tensile strength
c) Good toughness
d) Poor wear resistance
Answer: a [Reason:] Aluminum oxide (Al2O3) is regarded as the oldest engineering ceramic. They have excellent hardness and wear resistance. They are stiffer and stronger than steels. Their tensile and toughness properties, however, can be improved by mixing them with zirconium.
9. What is the tensile strength of aluminum oxide?
a) 175 MPa
b) 210 MPa
c) 415 MPa
d) 550 MPa
Answer: b [Reason:] Alumina has a medium tensile strength of 210 MPa and Young’s modulus of 3.86 * 105. Silicon carbide has a tensile strength of 175MPa, which is lower than alumina. The tensile strength of silicon nitride and sialons are 415 MPa and 550 MPa respectively.
10. Which among the following exhibits the highest thermal conductivity?
b) Silicon carbide
c) Silicon nitride
Answer: b [Reason:] Silicon carbide (SiC) has a high thermal conductivity of 83.6 W/m/K. It also has the highest Young’s modulus of 4.14 * 105 among the following. The thermal conductivities of alumina, silicon nitride, and sialon are 8.4, 25, and 21.3 W/m/K in that order.
1. How much copper is present in deoxidized copper?
a) > 99.9%
b) > 99.85%
c) > 99.5%
d) > 99.35%
Answer: b [Reason:] Deoxidized copper contains over 99.85% Cu, along with As, Fe, and Bi. It is mainly used to remove cuprous oxides and reduce porosity. Arsenic deoxidized copper and arsenic touch pitch copper contain over 99.5% and 99.35% copper respectively.
2. High conductivity copper is used ______
a) In electrical engineering
b) To reduce porosity
c) To raise softening temperature
d) To manufacture semiconductor elements
Answer: a [Reason:] High conductivity copper contains over 99.9% copper, less than 0.005% of both lead and iron, along with a low oxygen content. This copper finds its applications in the field of electrical engineering as it is a great conductor of electricity.
3. Which copper grade is used to manufacture semiconductors and particle accelerator components?
a) High conductivity copper
b) Deoxidised copper
c) Oxygen-free copper
d) Arsenic deoxidized copper
Answer: c [Reason:] Semiconductor and superconductor components require high chemical purity. Oxygen-free copper serves this purpose, as well as for high vacuum devices like particle accelerators. This copper is valued for its purity, rather than its electrical conductivity.
4. What is the melting point of Copper?
Answer: c [Reason:] Copper is a soft and ductile material with good electrical and thermal conductivities. Its melting point is 1084 and boiling point is 2562.
5. Brass is an alloy of copper and ______
c) Tin and zinc
Answer: a [Reason:] Brasses are alloys which are stronger than plain copper. They are primarily composed of copper and zinc, and may additionally contain tin, lead, aluminum etc. They can be used to cast molds, draw wires, roll sheets, and turned into tubes.
6. α brasses contain ______ of zinc
Answer: b [Reason:] Brasses are classified into two types depending on the amount of zinc contained in them. Brasses up to 36% zinc are known as brasses. They are relatively soft, ductile, and are easily cold worked. On the other hand, brasses with over 36% zinc are available in two different phases; they are stronger than brasses.
7. What is the appearance of copper?
Answer: d [Reason:] Pure copper generally appears in a reddish-orange color. It is a metal with a lustrous property. Brass, an alloy of copper, may appear red or white, depending on the amount of zinc.
8. Addition of tellurium to copper results in ________
a) High strength
b) Decreased electrical conductivity
c) Increased machinability
d) No effect
Answer: c [Reason:] When copper is added with tellurium, it gives a good machinability. Beryllium, chromium, or 1-3% lead can be added to increase strength. Cadmium also increases strength but reduces electrical conductivity.
9. _______ is an alloy of copper and tin.
Answer: b [Reason:] Bronze is a high strength an alloy made of copper and tin. It has a better corrosion resistance compared to brasses.
10. Yellow metal is more commonly known as ______
a) Cartridge brass
b) Naval brass
c) Admiralty brass
d) Muntz metal
Answer: d [Reason:] Muntz metal is a brass alloy, which is otherwise also known as yellow metal. It consists of 60% copper and 40% zinc. They are commonly used for extruding rods and tubes, and for making condenser or heat exchanger plates.
11. Which brass alloy has a high tensile strength and can be used for cast molding?
a) Manganese brass
b) Free cutting brass
c) Standard brass
d) Gilding metal
Answer: a [Reason:] Manganese brass has a good tensile strength compared to other brass alloys. It is also known as high tensile brass. They can be hot worked, and are commonly used for making pump-rods, and marine castings.
12. Which brass alloy is used to make imitation jewelry and decorative work?
a) Standard brass
b) Admiralty brass
c) Free cutting brass
d) Gilding metal
Answer: d [Reason:] Gilding metal, which is also known as commercial metal, is used for making coins, medals, artificial jewelry, and decorative work. It consists of 90% copper and 10% zinc. It is gold in appearance and had a good ductility.
13. Which brass alloy is suitable for high-speed machining?
a) Gilding metal
b) High tensile brass
c) Leaded brass
d) Muntz metal
Answer: c [Reason:] Leaded brass is used for high-speed machining due to its excellent strength and heat resistance. It contains 59% Cu, 39% Zn, and 2% Pb. It is also known as free cutting brass.