41. Which of the following polymers is an addition polymer?
- a) Dacron
- b) Nylon-6,6
- c) Polystyrene
- d) Bakelite
Answer: c) Polystyrene
Explanation: Polystyrene is formed by the addition polymerization of styrene monomers, without the elimination of any by-products.
42. Which of the following statements is correct about thermoplastic polymers?
- a) They cannot be remolded once set.
- b) They soften on heating and harden on cooling.
- c) They form extensive cross-links.
- d) They are used for electrical insulators.
Answer: b) They soften on heating and harden on cooling.
Explanation: Thermoplastic polymers can be softened by heating and reshaped repeatedly, unlike thermosetting polymers which harden permanently after setting.
43. The polymer used in bulletproof materials is:
- a) PVC
- b) Nylon-6
- c) Kevlar
- d) Teflon
Answer: c) Kevlar
Explanation: Kevlar is a high-strength polymer used in bulletproof vests due to its exceptional strength-to-weight ratio and durability.
44. The polymerization of vinyl chloride gives:
- a) Polyvinyl chloride
- b) Polyethylene
- c) Polystyrene
- d) Polypropylene
Answer: a) Polyvinyl chloride
Explanation: Polyvinyl chloride (PVC) is produced by the polymerization of vinyl chloride monomers through an addition polymerization process.
45. Which of the following is a characteristic of thermosetting polymers?
- a) They can be softened by heating.
- b) They have a linear structure.
- c) They form extensive cross-linking on heating.
- d) They are flexible.
Answer: c) They form extensive cross-linking on heating.
Explanation: Thermosetting polymers undergo cross-linking when heated, which makes them rigid and heat-resistant. Once set, they cannot be reshaped.
46. Which of the following is a natural polymer?
- a) Bakelite
- b) Cellulose
- c) Nylon-6
- d) Polyvinyl chloride
Answer: b) Cellulose
Explanation: Cellulose is a natural polymer made of glucose monomers. It is found in the cell walls of plants and is the most abundant organic polymer on Earth.
47. Which polymer is used to make fabrics for clothing?
- a) Polyvinyl chloride
- b) Polyester
- c) Bakelite
- d) Polystyrene
Answer: b) Polyester
Explanation: Polyester is a synthetic polymer used to make fabrics for clothing because of its durability, strength, and resistance to shrinking and wrinkling.
48. Which of the following is a biodegradable polymer?
- a) Polystyrene
- b) Polypropylene
- c) Polyhydroxybutyrate (PHB)
- d) Polyvinyl chloride
Answer: c) Polyhydroxybutyrate (PHB)
Explanation: PHB is a biodegradable polymer produced by bacteria. It is used in medical applications and packaging, where biodegradability is important.
49. Which polymer is produced by the polymerization of acrylonitrile?
- a) Nylon
- b) PVC
- c) Polyacrylonitrile (PAN)
- d) Polypropylene
Answer: c) Polyacrylonitrile (PAN)
Explanation: Polyacrylonitrile is a polymer produced by the polymerization of acrylonitrile. It is used in the production of fibers like acrylics.
50. Which polymer is used to make lightweight and strong packaging materials?
- a) Bakelite
- b) Polyethylene
- c) Kevlar
- d) Nylon
Answer: b) Polyethylene
Explanation: Polyethylene is widely used in packaging materials due to its light weight, strength, and flexibility. It is commonly used in plastic bags and containers.
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