11. Which of the following is a biodegradable polymer?
- a) Polyvinyl chloride (PVC)
- b) Polythene
- c) Polyhydroxybutyrate (PHB)
- d) Polystyrene
Answer: c) Polyhydroxybutyrate (PHB)
Explanation: PHB is a biodegradable polymer produced by microorganisms. It is a biopolymer that decomposes naturally, unlike synthetic polymers like PVC or polythene.
12. Which of the following monomers is used in the manufacture of Buna-S rubber?
- a) Ethylene and propylene
- b) Butadiene and styrene
- c) Acrylonitrile and butadiene
- d) Isoprene and isobutylene
Answer: b) Butadiene and styrene
Explanation: Buna-S is a copolymer made from the polymerization of butadiene and styrene. It is a synthetic rubber widely used in the production of tires.
13. Which of the following is a step-growth polymerization process?
- a) Polymerization of ethene to polyethylene
- b) Formation of Nylon-6,6
- c) Polymerization of styrene
- d) Polymerization of vinyl chloride
Answer: b) Formation of Nylon-6,6
Explanation: Step-growth polymerization involves the reaction of bifunctional or multifunctional monomers, such as hexamethylene diamine and adipic acid, to form polymers like Nylon-6,6.
14. Which of the following is a thermoplastic polymer?
- a) Bakelite
- b) Polyethylene
- c) Vulcanized rubber
- d) Melamine
Answer: b) Polyethylene
Explanation: Polyethylene is a thermoplastic, meaning it can be melted and reshaped multiple times. Bakelite and melamine are thermosetting polymers, while vulcanized rubber is an elastomer.
15. Low-density polyethylene (LDPE) differs from high-density polyethylene (HDPE) in:
- a) Melting point
- b) Flexibility
- c) Degree of branching
- d) All of the above
Answer: d) All of the above
Explanation: LDPE has a lower melting point, higher flexibility, and a more branched structure than HDPE, which has a more linear structure and is denser.
16. Which polymer is commonly used in the manufacturing of plastic bottles and containers?
- a) Polyvinyl chloride (PVC)
- b) Polyethylene terephthalate (PET)
- c) Polystyrene
- d) Nylon
Answer: b) Polyethylene terephthalate (PET)
Explanation: PET is widely used in the production of plastic bottles, containers, and packaging materials due to its strength, transparency, and recyclability.
17. Which of the following statements about vulcanization is correct?
- a) It increases the elasticity of rubber.
- b) It involves the addition of chlorine.
- c) It increases the solubility of rubber in organic solvents.
- d) It converts rubber into a thermoplastic polymer.
Answer: a) It increases the elasticity of rubber.
Explanation: Vulcanization involves heating rubber with sulfur to form cross-links between polymer chains, enhancing elasticity, durability, and heat resistance.
18. Polystyrene is prepared by the polymerization of:
- a) Ethylene
- b) Propylene
- c) Styrene
- d) Vinyl chloride
Answer: c) Styrene
Explanation: Polystyrene is formed by the polymerization of styrene monomers through an addition polymerization process.
19. Which of the following is not a step in free radical polymerization?
- a) Initiation
- b) Propagation
- c) Termination
- d) Hydrolysis
Answer: d) Hydrolysis
Explanation: Free radical polymerization involves three main steps: initiation, propagation, and termination. Hydrolysis is not involved in this type of polymerization.
20. The polymer obtained from the copolymerization of styrene and acrylonitrile is called:
- a) SBR
- b) Polyacrylonitrile
- c) SAN
- d) ABS
Answer: c) SAN
Explanation: SAN is a copolymer of styrene and acrylonitrile. It is used in the production of plastic products due to its durability and strength.
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