JEE Advanced 2022 Paper 2 Q14 Chemistry Biomolecules & Polymers Polymers & Copolymers Medium

JEE Advanced 2022 Paper 2 · Q14 · Polymers & Copolymers

Among the following, the correct statement(s) about polymers is(are):

  1. A. The polymerization of chloroprene gives natural rubber.
  2. B. Teflon is prepared from tetrafluoroethene by heating it with persulphate catalyst at high pressures.
  3. C. PVC are thermoplastic polymers.
  4. D. Ethene at 350-570 K temperature and 1000-2000 atm pressure in the presence of a peroxide initiator yields high density polythene.
JEE Advanced multi-correct — pick every correct option, then check.
Reveal answer + step-by-step solution

Correct answer:B, C

Solution

(A) Polymerisation of chloroprene (2-chloro-1,3-butadiene) gives NEOPRENE (a synthetic rubber), NOT natural rubber. Natural rubber is cis-1,4-polyisoprene (from isoprene). (A) is WRONG.

(B) Teflon = polytetrafluoroethene (PTFE) is industrially made by free-radical polymerisation of tetrafluoroethene (CF$_2$=CF$_2$) using a peroxydisulfate (persulphate) initiator at elevated pressure. (B) is CORRECT.

(C) PVC (polyvinyl chloride) is a thermoplastic polymer (softens on heating, hardens on cooling, recyclable). CORRECT.

(D) Ethene at 350–570 K, 1000–2000 atm with a peroxide initiator yields LOW density polyethylene (LDPE) — the free-radical, high-pressure process gives branched LDPE. HIGH-density polyethylene (HDPE) is made by Ziegler–Natta catalysis at low pressure. (D) is WRONG.

Correct options: B, C.

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