Polymers Test

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Polymers Test - 41

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Weekly Quiz Competition

Question 1
1 / -0

'Accelerators', in rubber technology, are organic sulphur compounds used as:

A
catalysts for vulcanization

B
carbon black binders for tyres

C
fillers

D
speed increasers for nylon tyres

Solution

Accelerators speed up the reaction of sulphur with polymer to improve the economics of manufacture and prevent degradation which would otherwise occur on prolonged heating.
Question 2
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Which of the following is a monomer of natural rubber?

A
Chloroprene

B
Caprolactam

C
Urea

D
None of these

Solution

Monomer of Natural Rubber (Polyisoprene) is isoprene.
Question 3
1 / -0

Identify the type of polymer.
(i) - A - A - A - A - A - A-
(ii) - A - B - B - A - A - A - B - A -

A
(i) Homopolymer, (ii) Copolymer

B
(i) Natural polymer, (ii) Synthetic polymer

C
(i) Linear polymer, (ii) Branched polymer

D
(i) Fibre, (ii) Elastomer

Solution

Homopolymer - If only one type of monomeric unit takes part to form a polymeric structure, it is called as a homopolymer.
Example = Glycogen, starch, chitin

Since (i) is made up of only A type of monomer, it is a homopolymer

Copolymer - If two types of monomeric units take part to form a polymeric structure, it is called as a copolymer.
Example = Nylon6-6, dacron, glyptal

Since (ii) is made up of A and B type of monomer, it is a copolymer.
Question 4
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Bakelite is an example of:

A
elastomer

B
fibre

C
thermoplastic

D
thermosetting polymer

Solution

Bakelite is an example of a thermosetting polymer and also a type of phenol-formaldehyde polymers. These are obtained by the condensation reaction of phenol with formaldehyde in the presence of either an acid or a base catalyst. The reaction starts with the initial formation of $$o-$$ and/or $$p-$$hydroxymethyl phenols derivatives, which further react with phenol to form compounds having rings joined to each other through $$-CH_2$$ groups.
Question 5
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The S in buna-S refers to:

A
sulphur

B
styrene

C
sodium

D
salicylate

Solution

The $$S$$ in buna-$$S$$ refers to styrene, it is ethenylbenzene as shown in the above image. Buna-$$S$$ and buna-$$N$$ both are the types of synthetic rubbers. The correct option is $$[B]$$.
Question 6
1 / -0

Bakelite is obtained from phenol by reaction with:

A
$$HCHO$$

B
$$(CH_{2}OH)_{2}$$

C
$$CH_{3}CHO$$

D
$$CH_{3}COCH_{3}$$

Solution

Bakelite is formed from phenol and formladehyde monomers.
Question 7
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Low-density polyethene (LDP) is used in the insulation of electricity carrying wires and manufacture of flexible pipes and squeeze bottles because:

A
it is tough, hard and rigid

B
it is chemically inert, tough, flexible and poor conductor of electricity

C
it is very tough, good conductor of electricity and flexible

D
it is chemically inert, very soft, water absorbent and poor conductor of heat

Solution

Method of the preparation of low-density polythene-
It is obtained by the polymerisation of ethene under high pressure of $$1000$$ to $$2000$$ atmospheres at a temperature of $$350 K$$ to $$570 K$$ in the presence of traces of dioxygen or a peroxide initiator (catalyst). The low-density polyethene (LDP) obtained through the free radical addition and H-atom abstraction has highly branched structure. Low-density polyethene is chemically inert and tough but flexible and a poor conductor of electricity.
The correct option is [B].
Question 8
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Which of the following is not true about high density polythene?

A
Tough

B
Hard

C
Inert

D
Highly branched
Solution
Properties of high-density polythene:
- High density due to close packing
- Chemically inert
- More tough and hard than low-density polythene
- High-density polythene has a linear structure.
Question 9
1 / -0

When cellulose from wood or cotton is cooked in large tanks containing caustic soda and then through a narrow slit into another tank containing acid, we get:

A
cellophane, a paper-like plastic

B
rayon, a textile fibre

C
bakelite, an insulator

D
unvulcanized rubber

Solution

When cotton is immersed in a solution of caustic soda, the swelling of cotton takes place; freed chains rearrange and reorient and when the caustic soda is removed, the chains form new bonds in the reorganized state. Because of the distortion of polymer network and changes in crystalline structure due to which cellophane is formed.
Question 10
1 / -0

Match the polymers given in column I with the monomers in column II and mark the appropriate choice.

A
(A) $$\rightarrow$$ (ii), (B) $$\rightarrow$$ (i), (C) $$\rightarrow$$ (iii), (D) $$\rightarrow$$ (iv)

B
(A) $$\rightarrow$$ (iii), (B) $$\rightarrow$$ (iv), (C) $$\rightarrow$$ (i), (D) $$\rightarrow$$ (ii)

C
(A) $$\rightarrow$$ (i), (B) $$\rightarrow$$ (iii), (C) $$\rightarrow$$ (ii), (D) $$\rightarrow$$ (iv)

D
(A) $$\rightarrow$$ (iv), (B) $$\rightarrow$$ (ii), (C) $$\rightarrow$$ (iii), (D) $$\rightarrow$$ (i)

Solution

A) $$\underset{Hexamethylenediamine }{NH_2 - (CH_2)_6 - NH_2} + \underset{Adipic\, acid}{COOH - (CH_2)_6 - COOH} \longrightarrow \underset{Nylon\, 6,6}{-\!\!\!(\overset{\displaystyle H}{\overset{|}{N}} - (CH_2)_6 -\overset{\displaystyle H}{\overset{|}{N}} - \overset {\overset{\displaystyle O}{||}}{C}- (CH_2)_4 -\overset{\displaystyle O}{\overset{||}{C}} -\!\!\!\!)_n}$$

D) $$\underset{Urea}{NH_2-CO - NH_2} + \underset{Formaldehyde}{HCHO} \longrightarrow \underset{Urea + formaldehyde}{-\!\!\!(NH - CO - NH - CH_2 -\!\!\!)_n}$$