Polymers — Page 3 | JEE Chemistry

Q21

Which one of the following is NOT a copolymer?

A Buna-S

B Neoprene

C PHBV

D Butadiene-styrene

Correct Answer

Option B

Solution

A copolymer is a polymer that consists of two or more different types of monomers.

Here are the options examined: Option A: Buna-S - It's a copolymer of butadiene and styrene.

Option B: Neoprene - It is made from the polymerization of chloroprene, so it is a homopolymer, not a copolymer.

Option C: PHBV - Polyhydroxybutyrate-co-valerate (PHBV) is a copolymer consisting of Polyhydroxybutyrate (PHB) and Polyhydroxyvalerate (PHV).

Option D: Butadiene-styrene - This is another name for SBR, or styrene-butadiene rubber, and it's a copolymer of butadiene and styrene.

Q22

Which of the following is not an example of a condensation polymer?

A Nylon 6,6

B Dacron

C Buna-N

D Silicone

Correct Answer

Option C

Solution

Nylon 6,6 is a condensation polymer of hexamethylene diamine and adipic acid Dacron is a condensation polymer of terephthalic acid and ethylene glycol.

Buna- $\mathrm{N}$ is an addition polymer of 1, 3-butadiene and acrylonitrile Silicone is a condensation polymer of dialkyl silanediol.

Q23

Polymer formation from monomers starts by

A condensation reaction between monomers

B coordinate reaction between monomers

C conversion of monomer to monomer ions by protons

D hydrolysis of monomers

Correct Answer

Option A

Solution

Polymerisation starts either by condensation or addition reactions between monomers.

Condensation polymers are formed by the combination of monomers with the elimination of simple molecules.

Where as the addition polymers are formed by the addition together of the molecules of the monomer or monomers to form a large molecule without elimination of anything.

Q24

Which statement is correct?

A Buna-N is a natural polymer.

B Synthesis of Buna-S needs nascent oxygen.

C Buna-S is a synthetic and linear thermosetting polymer.

D Neoprene is an addition copolymer used in plastic bucket manufacturing.

Correct Answer

Option B

Solution

Buna-S is an elastomer Buna-N is a synthetic polymer Buna-S is polymerised by addition polymerisation method which needs radical initiator for chain propagation step.

Nascent oxygen can be used as an Radical initiator.

Neoprene is a synthetic rubber.

Q25

Match the following .tg .tg Column A Column B

List - I		List - II
(a)	Nylon 6	(I)	Natural Rubber
(b)	Vulcanized Rubber	(II)	Cross Linked
(c)	cis-1, 4-polyisoprene	(III)	Caprolactam
(d)	Polychloroprene	(IV)	Neoprene

A

\mathrm{a} \rightarrow \mathrm{III}, \mathrm{b} \rightarrow \mathrm{II}, \mathrm{c} \rightarrow \mathrm{I}, \mathrm{d} \rightarrow \mathrm{IV}

B

\mathrm{a} \rightarrow \mathrm{II}, \mathrm{b} \rightarrow \mathrm{III}, \mathrm{c} \rightarrow \mathrm{IV}, \mathrm{d} \rightarrow \mathrm{I}

C

\mathrm{a} \rightarrow \mathrm{IV}, \mathrm{b} \rightarrow \mathrm{III}, \mathrm{c} \rightarrow \mathrm{I}, \mathrm{d} \rightarrow \mathrm{II}

D

\mathrm{a} \rightarrow \mathrm{III}, \mathrm{b} \rightarrow \mathrm{IV}, \mathrm{c} \rightarrow \mathrm{I}, \mathrm{d} \rightarrow \mathrm{II}

Correct Answer

Option A

Solution

Nylon 6 is a synthetic polymer made from caprolactam, so it corresponds to Column A, option (c), which matches with Column B, option (I).

Vulcanized rubber is rubber that has been treated with sulfur or other additives to make it more durable, so it corresponds to Column A, option (b), which matches with Column B, option (II).

Cis-1,4-polyisoprene is a naturally occurring polymer found in natural rubber, so it corresponds to Column A, option (a), which matches with Column B, option (III).

Polychloroprene is a synthetic polymer used to make neoprene, a type of synthetic rubber, so it corresponds to Column A, option (d), which matches with Column B, option (IV).

Therefore, the correct matching is:

\mathrm{a} \rightarrow \mathrm{III}, \mathrm{b} \rightarrow \mathrm{II}, \mathrm{c} \rightarrow \mathrm{I}, \mathrm{d} \rightarrow \mathrm{IV}

Option A is the correct answer.

Q26

Which of the following polymer is used in the manufacture of wood laminates?

A Melamine formaldehyde resin

B Urea formaldehyde resin

C cis-poly isoprene

D Phenol and formaldehyde resin

Correct Answer

Option B

Solution

Urea-formaldehyde resin is used in wood laminates.

Q27

Which of the following statements is not true ?

A Step growth polymerisation requires a bifunctional monomer.

B Nylon 6 is an example of step-growth polymerisation.

C Chain growth polymerisation includes both homopolymerisation and copylymerisation.

D Chain growth polymerisation involves homopolymerisation only.

Correct Answer

Option D

Solution

Chain growth polymerisation is an addition polymerisation which involves homopolymerisation and copolymerisation both.

Q28

Poly

\beta

–hydroxybutyrate-co-

\beta

-hydroxyvalerate (PHBV) is a copolymer of

A 2-hydroxybutanoic acid and 3-hydroxypentanoic acid

B 3-hydroxybutanoic acid and 2-hydroxypentanoic acid

C 3-hydroxybutanoic acid and 3-hydroxypentanoic acid

D 3-hydroxybutanoic acid and 4-hydroxypentanoic acid

Correct Answer

Option C

Solution

PHBV is obtained by copolymerization of 3-Hydroxybutanioic acid and 3-Hydroxypentanoic acid.

Q29

The polymer formed on heating Novolac with formaldehyde is :

A Bakelite

B Polyester

C Melamine

D Nylon 6, 6

Correct Answer

Option A

Solution

Novolac + formaldehyde $\to$ Bakelite

Q30

Vulcanization of rubber is carried out by heating a mixture of

A isoprene and styrene

B neoprene and sulphur

C isoprene and sulphur

D neoprene and styrene

Correct Answer

Option C

Solution

When a mixture of isoprene and sulphur is heated, isoprene gets polymerised to natural rubber and then vulcanization of natural rubber with sulphur takes place.