51. Low density polythene is prepared by
A
Free radical polymerisation
B
cationic polymerisation
C
anionic polymerisation
D
Ziegler-Natta polymerisation
Answer :
Free radical polymerisation
52. On complete hydrogenation, natural rubber produces
A
ethylene-propylene copolymer
B
vulcanised rubber
C
polypropylene
D
polybutylene
Answer :
ethylene-propylene copolymer
53.
Match the column I with column II and mark the appropriate choice.
Column I
Column II
a.
Natural polymer
1.
Rayon
b.
Addition polymer
2.
Bakelite
c.
Copolymer
3.
Silk
d.
Semi-synthetic polymer
4.
Neoprene
A
a - 1, b - 2, c - 4, d - 3
B
a - 3, b - 4, c - 2, d - 1
C
a - 2, b - 3, c - 1, d - 4
D
a - 4, b - 1, c - 3, d - 2
Answer :
a - 3, b - 4, c - 2, d - 1
54. In vulcanization of rubber
A
sulphur reacts to form a new compound
B
sulphur cross-links are introduced
C
sulphur forms a very thin protective layer over rubber
D
all statements are correct
Answer :
sulphur cross-links are introduced
55. During addition polymerisation of ethene molecules, the initiator like benzoyl peroxide, acetyl peroxide, $$tert$$ - butyl peroxide, etc. are added. Their function is to
A
ensure anti-Markownikoff's addition of molecules to form polymer
B
give cations during the reaction which join together to form bigger molecules
C
decrease the temperature of the reaction mixture
D
generate free radical which adds to the monomer to give bigger free radical
Answer :
generate free radical which adds to the monomer to give bigger free radical
56. Which of the following organic compounds polymerises to form the polyester dacron?
A
Propylene and $$para$$ $$ - HO - \left( {{C_6}{H_4}} \right) - OH$$
B
Benzoic acid and ethanol
C
Terephthalic acid and ethylene glycol
D
Benzoic acid and para $$ - HO - \left( {{C_6}{H_4}} \right) - OH$$
Answer :
Terephthalic acid and ethylene glycol
57. The condensation of hexamethylenediamine with sebacoyl chloride at \[525\,K\] gives
A
nylon - 6, 20
B
nylon - 6, 01
C
nylon - 6, 10
D
None of these
Answer :
nylon - 6, 10
58. Which of the following statements is false ?
A
Artificial silk is derived from cellulose.
B
Nylon - 6, 6 is an example of elastomer.
C
The repeat unit in natural rubber is isoprene.
D
Both starch and cellulose are polymers of glucose.
Answer :
Nylon - 6, 6 is an example of elastomer.
59. Formation of nylons and polyesters are called step growth polymerisation because
A
the polymers are formed by adding a monomer step by step
B
the polymers are formed by condensation and monomers are joined by loss of simple molecules like water
C
the monomers used for condensation are unsaturated molecules
D
the polymers are formed by addition of a large number of free radicals formed by monomers
Answer :
the polymers are formed by condensation and monomers are joined by loss of simple molecules like water
60. Which of the following is a polyamide?
A
Bakelite
B
Terylene
C
Nylon-66
D
Teflon
Answer :
Nylon-66