A large numberof monomers (Simple molecules) combine together to form a larger molecule ( macro molecule) called as polymer. Each polymer is made up of a repeating structural unit. A polymer is said to be homopolymer if the structural unit is derived from one type of monomer molecules. if the repeating structural unit of a polymer is derived from more than one different types of monomers, the polymer is said to a copolymer. The homopolymers as well as copolymers may be formed by addition or condensation reactions. Alekenes and dienes polymerize by additions (Chain growth) mechanism involving carbocations, carbanions or free radical intermeidates. Dienes (Chloroprene) polymerise by 1, 4 addition mechanism to give cis or trans polymers. Natural rubber is, however, cis-polyisoprene. Natural rubber is quite soft and tacky but these properties can be improved by a process called vulcanization.
In contrast, bifunctional monomer molecules undergo condensation or step-growth polymerization. Polymers which can be heated and reshpaed as many times as desired are called thermoplastics (polyethene, polystyrene, PVC, teflon etc). While those which can be heated onoy once to give a particular shape are called thermosetting polymers (bakelite, melmac etc.)
Chloroprene is the repeating unit in:

Options

A. Polystyrene
B. Neoprene
C. PVC
D. Polythene.

Answer

B