Among the following, the correct statement(s) about polymers is(are)
- A
The polymerization of chloroprene gives natural rubber.
- B
Teflon is prepared from tetrafluoroethene by heating it with persulphate catalyst at high pressures.
- C
PVC are thermoplastic polymers.
- D
Ethene at 350-570 K temperature and 1000-2000 atm pressure in the presence of a peroxide initiator yields high density polythene.
(A) Natural rubber is cis-polyisoprene, obtained from isoprene (2-methylbuta-1,3-diene). Chloroprene polymerizes to neoprene, a synthetic rubber. Incorrect.
(B) Teflon (polytetrafluoroethylene) is manufactured from tetrafluoroethene under high pressure using a persulphate (or other free-radical) initiator. Correct.
(C) PVC (polyvinyl chloride) is a thermoplastic; it softens on heating and is used in pipes, flooring, etc. Correct.
(D) The conditions described (350–570 K, 1000–2000 atm, peroxide initiator) are the classical high-pressure free-radical process for low-density polyethylene (LDPE), not HDPE. HDPE is made by Ziegler–Natta catalysis at much lower pressures. Incorrect.
(B), (C).
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