This set of Building Construction Multiple Choice Questions & Answers (MCQs) focuses on “Plastics”.
1. Which of the following polymers is obtained by condensation polymerization?
a) Polyethene
b) Polystyrene
c) Polyvinylchloride
d) Carbamide
View Answer
Explanation: Carbamide is obtained by condensation polymerization. Polyethene, polystyrene and polyvinylchloride are obtained by addition polymerization.
2. Plastics are divided into thermoplastic and thermosetting on the basis of their ________
a) Behaviour with respect to heating
b) Structure
c) Physical properties
d) Mechanical properties
View Answer
Explanation: The classification of plastics is done on the basis of their behaviour with respect to heating, structure, physical properties and mechanical properties. Plastics are divided into thermoplastic and thermosetting on the basis of their behaviour with respect to heating.
3. In addition polymerization, the molecular weight of the resulting polymer is the same as the sum of the molecular weights of the reacting molecules.
a) True
b) False
View Answer
Explanation: Polymerization is the process of converting monomers into polymers. In addition, polymerization, the molecular weight of the resulting polymer is the same as the sum of the molecular weights of the reacting molecules.
4. Which of the following statements about thermosetting plastics is not true?
a) It is possible to change their shape on heating
b) They are durable and strong
c) They are available in a variety of colours
d) They become rigid on heating
View Answer
Explanation: Thermosetting plastics become rigid on heating and it is possible to change their shape. They are durable and strong and are available in a variety of colours.
5. Which of the following types of plastics have a high modulus of elasticity?
a) Rigid plastics
b) Semi-rigid plastics
c) Soft plastics
d) Elastomers
View Answer
Explanation: Rigid plastics have a high modulus of elasticity. Semi-rigid plastics have a medium modulus of elasticity. Soft plastics and elastomers have a low modulus of elasticity.
6. Which of the following is a thermoplastic resin?
a) Casein
b) Phenol formaldehyde
c) Cellulose
d) Urea-formaldehyde
View Answer
Explanation: Just like plastics, resins are also classified into thermoplastic resins and thermosetting resins depending on their behaviour with respect to heating. Cellulose is an example of thermoplastic resin. Phenol formaldehyde, casein and urea-formaldehyde are examples of thermosetting resins.
7. Which of the following resins is also known as acrylic?
a) Methyl methacrylate
b) Alkyd
c) Styrene
d) Vinyl
View Answer
Explanation: Methyl methacrylate is a thermoplastic resin which is also known as acrylic. This resin is derived from coal petroleum and water. Plastics obtained from this resin are used for roof lights, safety glass, etc.
8. The components of alkyd are _______
a) Alcohol and phthalic acid
b) Glycol and formic acid
c) Glycerine and phthalic acid
d) Glycerine and formic acid
View Answer
Explanation: Alkyd is a thermoplastic resin that is used to prepare thin films of plastics. The components of alkyd are glycerine and phthalic acid.
9. Which of the following statements about styrene is not true?
a) Styrene is light in weight
b) It has a low electrical resistance
c) Water absorption of styrene is low
d) Styrene is not easily attacked by chemicals
View Answer
Explanation: Styrene is a thermoplastic resin which is not easily attacked by chemicals and which is light in weight. Water absorption of styrene is low and this resin has a very high electrical resistance.
10. Which of the following resins is obtained by the precipitation of milk with acids?
a) Vinyl
b) Casein
c) Cellulose
d) Alkyd
View Answer
Explanation: Casein is a thermosetting resin which is obtained by the precipitation of milk with acids. Plastics obtained from casein are used for buttons, buckles, etc.
11. Melamine is derived from ________
a) Silicon carbide
b) Calcium silicate
c) Calcium carbide
d) Calcium sulphate
View Answer
Explanation: Melamine is derived from calcium carbide. It forms a thermosetting resin named melamine-formaldehyde on reaction with formaldehyde. Plastics obtained from this resin are widely used for electrical insulators.
12. Homogeneous plastic is made of the chain containing only carbon atoms while heterogeneous plastic consists of the chain containing carbon and oxygen, nitrogen and other elements.
a) True
b) False
View Answer
Explanation: Plastics are divided into two groups on the basis of their structure – homogeneous and heterogeneous. Homogeneous plastic is made of the chain containing only carbon atoms while heterogeneous plastic consists of the chain containing carbon and oxygen, nitrogen and other elements.
13. Hexamethylene tetramine serves as a hardener for ________
a) Cellulose
b) Polystyrene
c) Polyvinylchloride
d) Phenol formaldehyde
View Answer
Explanation: Hexamethylene tetramine serves as a hardener for phenol-formaldehyde. A hardener is a compound that is used to increase the hardness of resins.
14. Tributyl phosphate is an example of ___________
a) Hardener
b) Pigment
c) Plasticizer
d) Filler
View Answer
Explanation: Tributyl phosphate is an example of a plasticizer. Plasticizers are used to improve plasticity. They impart softness to plastics and they should be chemically inert.
15. Which of the following is not a property of plastics?
a) Plastics are not ductile
b) Plastics are organic in nature
c) Plastics have good electric insulation properties.
d) PVC plastics are inflammable
View Answer
Explanation: Plastics are organic in nature. They are not ductile but have good electric insulation properties. Plastics made of PVC are non-inflammable.
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