Multiple choice question for engineering
1. Which of the following is not a characteristic trait of polymer materials?
a) Low density
b) Resistant to chemical attack
c) Low cost
d) High strength
Answer: d [Reason:] Polymers are a large group of repeating units of small molecules. They have a low density and cost, with good thermal and electrical insulation. They are also easy to fabricate and are resistant to chemical attack. Their low strength and stiffness can be improved by fiber reinforcement.
2. The number of repeating units in a polymer is known as __________
b) degree of polymerization
Answer: b [Reason:] Monomers are small molecules which combine repeatedly to form a polymer. The number of these repetitive units in one molecule is referred to as the degree of polymerization. It is also known as D.P. value.
3. A polymer made of identical monomer units is called ______
b) Linear polymer
d) Branched polymer
Answer: a [Reason:] When all the monomer units in a chain are of the same type, they are called homopolymers. When a polymer is created using different types of monomers, it is a copolymer. For example, -M-M-M-M- is a homopolymer and -M1-M2-M1-M2- is a copolymer. Linear and branched polymers are types of homopolymers.
4. Liquid or gas polymers having short chains and low molecular weights are known as _____
Answer: d [Reason:] Oligo-polymers are available in liquid or gas forms which have very short chains. They have a low molecular weight of the order of 100 g/mol. High-polymers have high molecular weights between 10000 to 1000000 g/mol.
5. Which molecular structure does the below figure represent?
Answer: c [Reason:] Cross-linked polymers are a type of homopolymers. They are formed when linear chains are joined together at various points. This is done due to the presence of covalent bonds.
6. Which molecular structure does the figure represent?
Answer: c [Reason:] Block copolymers are those containing identical monomers in blocks along the chain. Each block may contain equal to or more than two similar molecules. These blocks alternate between the two different types of monomers.
7. Which figure represents the branched molecular structure?
Answer: b [Reason:] Branched polymers are those in which branches of monomeric chains are connected to the main chain. Linear polymers are single line chains, whereas cross-linked polymers are joined from one chain to another. Network polymers are three-dimensional chains of monomeric units.
8. Which of the following figures represent a Graft copolymer structure?
Answer: d [Reason:] In graft copolymers, side branches of homopolymers are connected to the main chain. The side branches and main chain are composed of different monomers. Random copolymers have different monomers in random positions, while alternating polymers have different monomers in alternate places. Block copolymer is a set of blocks of different monomeric units.
9. Which of the following types of polymers is a copolymer?
Answer: a [Reason:] A graft polymer is a copolymer type in which the side branches of homopolymers are connected to the main chain. Random, alternating, and block are the other types of copolymers. Homopolymers exist as linear, branched, cross-linked, and network type.
10. Which of the following is not a stage of addition polymerization?
Answer: d [Reason:] Addition polymerization is a process by which similar monomers are combined to form long chain molecules. It involves initiation, propagation, and termination. This process is also known as chain reaction polymerization.
11. Addition of different types of monomers to form polymer chains is known as _______
a) Chain reaction polymerization
Answer: b [Reason:] Copolymerization is a type of addition polymerization involving different monomers. Copolymers are widely used in plastics. For example, styrene and butadiene combines to form a copolymer.
12. What is the rate of growth of chains in condensation polymerization?
a) 10-2 to 102 seconds
b) 10 minutes
c) Hours or days
Answer: c [Reason:] Condensation polymerization results in production of tri-functional monomers. These generally take a larger time for condensation; say a few hours to a few days. Addition polymerization takes 10-2 to 102 seconds for a chain growth.
13. Wood flour and silica flour are examples of ______
Answer: a [Reason:] Polymer additives are used to improve the properties and performance of polymers. Fillers are used for improving strength, stability, and reducing the overall cost A few examples of fillers are wood flour, silica flour, glass, sand, mica, etc.
14. Which polymer additives are added to improve flexibility?
Answer: b [Reason:] Plasticizers are polymer additives which improve flexibility, ductility, and toughness of a polymer. They reduce hardness and stiffness of the polymer, and increase the flow during the molding operation. Commonly used plasticizers are polyvinyl chloride and acetate copolymers.
15. Which of the following is an example of a stabilizer?
b) Polyvinyl chloride
c) Titanium dioxide
d) Antimony oxide
Answer: a [Reason:] Stabilizers in polymers help prevent deterioration of quality due to environmental and radiation effects. Hindered amines, hydroxyl phenyl benzotriazoles, and benzophenons are examples of commonly used stabilizers.
16. The optical opacity of a polymer can be controlled by using ______
c) Flame retardants
Answer: b [Reason:] Colorants are polymer additives which give the polymer a definite color and manage its optical opacity. They are also known as coloring agents or pigments. Metal oxides, sulfur diodes, and titanium dioxides are a few examples of colorants.
17. Which of the following is an example of flame retardants?
c) Antimony oxide
Answer: c [Reason:] Flame retardants are used to suppress flammability of a polymer. Common examples of flame retardants are antimony oxide, borates, bromates, and phosphates. Talc is used as a filler whereas dye is used as a colorant. Glyceride finds its application as a lubricant.
18. Which polymer additive is used to remove parts from molds?
Answer: c [Reason:] Lubricants are used to remove parts from molds, make surfaces slippery, and prevent them from sticking to each other. They are also known as slip agents. Common lubricant additives are silicone, waxes, fatty acid amides, glycerides, petrolatum etc.
19. Carbon fiber is an example of ________
d) Flame retardant
Answer: c [Reason:] Reinforcement is a type of polymer additive which is used to improve strength and rigidity of the polymer. Common examples of reinforcements are carbon fiber, glass fiber, fabrics, and mica. Mica is, sometimes, also used as a filler additive.
1. Which of the following is a requirement for thermal insulation in materials?
a) High specific gravity
b) High specific heat
c) Low thermal conductivity
Answer: c [Reason:] Thermal resistance of a material is the property which resists the flow (or rate of flow) of heat in a material. For a material to be a good thermal insulator, it must have low thermal conductivity. Other requirements of thermal insulators are low specific gravity and specific heat, along with being fire and vibration resistant.
2. How does moisture affect the thermal insulation of a body?
d) Becomes zero
Answer: a [Reason:] The thermal conductivity of water is largely greater than that of air. Due to this, the thermal insulation if the material is reduced by a large amount. Therefore, it is preferred that thermal insulators be generally resistant to moisture.
3. Which of the following is an example of an organic insulating material?
Answer: a [Reason:] Thermal insulation materials are classified as either organic or inorganic. Silk, wool, wood-pulp, and sawdust are a few examples of organic materials. Some common inorganic insulating materials are glass wool, slag, charcoal, and coke powder.
4. An insulating material named 85% magnesia can be used up to temperatures of _______
Answer: c [Reason:] 85% magnesia is a commonly used insulating material for industrial applications. It contains 85% magnesium carbonate along with 15% asbestos fiber. It can be used for covering surfaces up to 315oC.
5. An insulating material made from ______ is preferred for applications where vibration resistance is vital.
b) Magnesium carbonate
c) Rock wool
d) Cattle hair
Answer: d [Reason:] Sometimes cheaper alternatives are required for insulating applications. One such material is made from cattle hair and is chemically cleaned and felted. It can be used up to a temperature of 107oC and is used to withstand vibration and rough use.
6. A cork insulation with a waterproof binder is used for _______ surfaces.
Answer: c [Reason:] Some insulating materials are used for reducing the amount of heat in a cold storage plant. In such cases, a cork insulation (or rock wool) infused with a waterproof binder is used for the insulation.
7. Which of the following is a cause for an increase in insulation?
a) Increase in thickness
b) Decrease in thickness
c) Decrease in cost
d) Low density
Answer: a [Reason:] Generally, as the thickness of material increases, the rate of flow of heat decreases due to which the insulation takes place. This may lead to an increase in cost, but is not the main cause for such a response.
8. An electrically insulating material has a resistivity that is ____ times greater than that of copper.
Answer: d [Reason:] An electrical insulator resists the flow of current due to which it is considered as a poor conductor. A usual material has a resistivity that is just about 1021 bigger than that of copper. Common electrical insulating materials are air, glass, and polyethylene.
1. Which of the following properties is not associated with refractory metals?
a) High fusion temperature
b) High heat resistance
c) Good Corrosion resistance
d) High thermal coefficient of expansion
Answer: d [Reason:] Refractories are heat resistant materials capable of withstanding high temperatures of up to 2150oC. They have developed a good heat, corrosion, and abrasion resistance. They also possess a high fusion temperature. However, they have a low thermal coefficient of expansion.
2. Firebrick is an important raw material of refractory metals, which is made from ______
Answer: c [Reason:] Refractories are ceramic materials capable of withstanding high temperatures. They are formed by firebrick obtained from fireclay, along with other materials. However, non-clay refractories are being developed for specific requirements.
3. What kind of refractory can bauxite be grouped as?
a) Acid refractory
b) Basic refractory
c) Neutral refractory
d) Silica refractory
Answer: b [Reason:] Basic refractories are those which are rich in periclase or magnesia, sometimes with calcium, chromium, and other irons. The presence of silica in these may pose a threat to their performance. Magnesia and bauxite are examples of basic refractories.
4. Silica refractories are also known as ______ refractories
Answer: a [Reason:] Silica containing refractories are referred to as silica or acid refractories. They possess high-temperature capacity to withstand loads. The common types of acid refractories are silica, aluminum silica, alumina, and silimanite.
5. What is the fusion temperature of aluminum silica?
Answer: a [Reason:] Aluminum silica containing 46% Al2O3 and 54% SiO2 has an approximate fusion temperature of 1780oC. This refractory is a common type of acid refractory ceramic material. Silimanate and alumina have an approximate fusion temperature of 1900oC and 2050oC respectively.
6. Which of the following is an example of a neutral refractory?
Answer: d [Reason:] Chromite, along with graphite, is a common neutral refractory material. Chromite has an approximate fusion temperature of 2180oC while that of graphite is 3000oC. Dolomite and magnesia are basic refractories, whereas silica is an acid refractory.
7. What is the fusion temperature of Magnesia?
Answer: c [Reason:] Magnesia is a type of basic refractory material which has an approximate fusion temperature of 2800oC. The fusion temperature for silica is 1700oC while that for chromite is 2180oC. Basic refractories find applications in open hearth furnaces.
8. How much of alumina in weight percent is added to silica refractories?
a) 0.2 – 1.0
b) 1.1 – 1.5
c) 1.6 – 1.8
d) > 2.0
Answer: a [Reason:] Under the presence of alumina, silica refractories show a negative effect. Therefore they are limited to 0.2 – 1.0 wt %. These refractories are generally resistant to silica-rich slags.
9. Mullite is an example of ______ refractory.
Answer: d [Reason:] Special refractories are those materials having high purity and low porosity. Examples of special refractories are beryllia, zirconia, and mullite. These special refractories are comparatively expensive compared to the other types.
1. Which of the following coatings has a glass composition?
Answer: c [Reason:] Enamel (vitreous) is a protective coating composed of glass containing a metal substrate. Paint is composed of organic material, whereas galvanized coating has anodic metal, both of which contain metal substrate. The anodized coating has an Al composition with an aluminum substrate.
2. Which of the following is not a type of protective coating?
Answer: b [Reason:] A protective coating is generally defined as a layer of an inert substance which is applied to a material to prevent the chemical and electrochemical attack. These are classified into metallic, organic, and inorganic coatings.
3. An example of anodic coating is _____
Answer: a [Reason:] The anodic coating is a classification of a metallic coating of metals which are anodic to the base metal. Zinc, aluminum, and cadmium are examples of anodic coatings. Cathodic coatings include Cu, Ni, Ag, etc.
4. The method of immersing a material into a molten bath for coating is known as _____
b) Hot dipping
Answer: b [Reason:] Hot dipping is a method of metallic coating in which the product to be coated is dipped into a molten bath of the coating metal. Water pipe fittings coated with by the method of hot dipping.
5. Which of these methods uses a filler wire at a high-temperature flame?
a) Hot dipping
b) Metal spraying
c) Vapor plating
Answer: b [Reason:] In metal spraying, the surface to be coated is sprayed with the coating metal from a filler wire or powder at a high-temperature flame using a spray gun. A few materials like Al, Cu, Pb, Sn, and Zn can be coated by a spraying method.
6. The veneering of metals for coating is known as _______
b) Vapor plating
Answer: c [Reason:] Veneering of two or metals under a pressure is described as the cladding method of metallic coatings. The metal which needs to be applied the protective coating on is kept between two layers of the coating metal. This is then rolled into the required thickness, producing a protective coating.
7. Alclad is the cladding method where _____ is coated with pure aluminum.
Answer: a [Reason:] When two materials are veneered by a pressure, it is defined as the cladding process. The cladding of duralumin with pure aluminum is called Alclad.
8. Which method uses the powdered form of a coating to form the protective layer?
b) Hot dipping
c) Vapor plating
Answer: d [Reason:] Cementation is the process of alloying powdered coating metal with the base metal below melting point temperatures. Carburizing and sherardising are types of cementation processes. Al, Zn, Cr, and W are only a few metals used for cementation.
9. Phosphate coating and Chromate coating are classifications of ______ coatings.
Answer: c [Reason:] Chemical or electrochemical conversion is a form of an inorganic coating. They are used to improve corrosion resistance and for decoration. Phosphate, chromate, anodized, and chemical oxide coating are the various classifications of inorganic coatings.
10. The mixture of oil and a pigment is known as _____
Answer: b [Reason:] Paint is a form of an organic coating which is applied to protect against corrosion and to beautify surfaces. Oil is the wet component, whereas pigment is the dry material which adds color. The oil oxidizes to form a protective layer of the dry pigment.
11. A varnish is a mixture of _____ and oil.
Answer: a [Reason:] A mixture of natural or thermosetting resin and drying oil is used to form varnishes. These coatings do not contain pigments. However, reduced viscosity is obtained by adding turpentine to the mixture.
12. A mixture of oil and pigment in water is known as ______
Answer: b [Reason:] An emulsion is a suspension of particles of drying oil and pigment in water. It is an organic type of protective coating. Here, the water evaporates and the mixture of oil and pigment forms the required film. The emulsions are applied for decoration in household appliances.
13. Which organic coating is made from Lac dissolved in alcohol?
Answer: b [Reason:] Shellac is an organic protective coating which is made from the dissolved Lac in alcohol. It usually dries by evaporation of the solvent and leaves an organic finish. Lacquers contain nitrocellulose dissolved in the solvent.
14. Which common application do anodizing and galvanizing serve?
a) Corrosion resistance
b) Improved surface
c) Zinc coating
d) Increased strength
Answer: a [Reason:] Both anodizing and galvanizing processes are carried out to improve the corrosion resistance of materials. Additionally, anodizing improves the surface which helps in painting, whereas a layer of zinc is coating in galvanizing process.
1. What is the maximum permissible amount of ash on carbonization after coal is washed?
Answer: b [Reason:] As coal contains foreign substances, they need to be washed to rid them of this impurity. This is done either in gravity or floatation type machine. This coal, after washing and draining, must not exhibit ash content of more than 6% on carbonization.
2. What is the solid residue that remains after heating of coal in the absence of air?
Answer: b [Reason:] Coke is an important element used in iron-making and metallurgical applications. It is the solid and cellular residue that remains after bituminous coal is heated in the absence of air. This is done at a temperature above which thermal decomposition occurs.
3. What is the level of fineness to be achieved in crushed coal?
Answer: d [Reason:] The coal, after being washed, is blended to form a uniform configuration. This allows even low-grade coal to be used in operations. The blended mix is crushed to achieve a fine quality of 70-80% below a 3 mm mesh.
4. For how long must coke be burnt?
a) 2-3 hours
b) 6-8 hours
c) 18-24 hours
d) 30-36 hours
Answer: d [Reason:] Coal is subjected to destructive distillation at a temperature of 1150-1200oC.This forms hard and porous coke which has high carbon content. The burning of this coke lasts for 18-24 hours but is about 25% longer for foundry coke.
5. What is the appearance of oven coke?
c) Dark grey to light silver
d) Matte black
Answer: c [Reason:] Oven coke made either in by-product or beehive ovens may appear as a dull dark grey to light silver grey in color and are lustrous. They are hard and may appear with a few cracks and fractures.
6. Which of the following factors are not used to evaluate the quality of coke?
a) Size and shape
d) Electrical resistivity
Answer: d [Reason:] High-quality foundry coke typically contains a reduced amount of volatile matter, ash, and sulfur. This quality is generally determined by evaluating the physical, chemical, and thermal properties of coke.
7. Which of the following is not an advantage of coke over coal?
c) Low smoke
Answer: a [Reason:] Coke is a porous material that burns rapidly. It produces little to no smoke and contains zero water content. Coal, however, is a naturally occurring substance that is purer than coke.
8. What is the temperature at which low-temperature coke is prepared?
Answer: c [Reason:] Low-temperature coke is primarily used for the production of gas. It is produced at a temperature ranging between 450 and 700oC. It may also be used for making fuel briquettes.
9. What is high-temperature coke used for?
b) Production of gas
c) Fuel briquettes
Answer: a [Reason:] High-temperature coke is produced by operation at around 1000oC. It is otherwise known as metallurgical coke. This coke finds application in iron making processes and melting of ferrous and non-ferrous metals and alloys.
10. ________ is produced due to a chemical reaction between two or more substances.
a) Synthetic resin
b) Metallurgical coke
Answer: a [Reason:] Synthetic resins are defined as those man-made products formed as a result of a chemical reaction of two or more substances. This is usually carried out in the presence of heat or a catalyst. These resins include synthetic rubbers and silicones.
11. Neoprene was originally known as ________
a) Phenol formaldehyde
d) Polyvinyl halides
Answer: c [Reason:] Polychloroprene was the first synthetic elastomer discovered in 1931. It originated in Nieuwland and has since been known as Neoprene. This led to the discovery of several types of synthetic polymers.
12. Which of the following is not an application of synthetic resins?
c) Thermal insulation
d) Ion exchange
Answer: c [Reason:] Synthetic resin is a polymer formed artificially by chemical reaction. It is used in textiles, paints, and plastics. Some special synthetic resins are used as ion exchange media.
13. What is Portland cement primarily composed of?
Answer: b [Reason:] Portland cement is a common binder used for civil construction purposes. It mainly consists of calcium oxide (over 42%) with carbon dioxide (over 35%), followed by small quantities of Fe2O3, MgO, Al2O3, and over 15% of SiO2.
14. At what temperature is limestone heated to make Portland cement?
Answer: c [Reason:] Portland cement is manufactured by heating limestone and other raw materials at 1450oC in a kiln. This process is known as calcination. Here, calcium carbonate (limestone) releases carbon dioxide, which in turn becomes calcium oxide CaO.
15. The hardening process of Portland cement is known as _______
Answer: c [Reason:] Portland cement hardens and sets by capturing water. This involves intricate chemical reactions which may take up to 24 hours. This process, known as hydration, also causes bonding.
16. After burning of raw materials, Portland cement involves blending with ______
a) 3% baryte
b) 3% anhydrite
c) 3% hanksite
d) 3% gypsum
Answer: d [Reason:] Raw materials are ground to 200 mesh and burnt in a cement kiln. After burning, the resultant, called clinker, is ground to 325 mesh and blended with 3% gypsum. It is then stored in a cement silo, ready for use.
17. Which of the following cements are not used as a cement replacement?
a) Siliceous fly ash
b) Calcareous fly ash
c) Silica fume
d) Slag cement
Answer: c [Reason:] Siliceous fly ash, calcareous fly ash, and slag cement are common cements generally used as replacements of cement. Silica fume, on the other hand, is generally used as a property enhancer.
18. What is the specific gravity of Portland cement?
Answer: a [Reason:] Specific gravity is defined as the ratio of the density of a material to the density of a reference material. Portland cement has a higher specific gravity compared to other common cements. The specific gravities of Portland cement, slag cement, calcareous fly ash, and silica fume are 3.15, 2.94, 2.65, and 2.22 in that order.
19. White Portland cement is obtained due to sintering at _______
Answer: c [Reason:] White Portland cement is similar to ordinary and grey Portland cement in most aspects. This differs from other types of Portland cement due to their white appearance, which is a result of low Fe2O3 content. As opposed to the normal operating at 1450oC, white Portland cement requires sintering at 1600oC.