Question

Isotactic polypropylene polymer is one, in which:

• A. all methyl groups are on one side of the extended chain. It is a highly crystalline, has high melting point and forms strong fibres
• B. the methyl groups present alternates regularly from one side to the other
• C. the methyl groups are distributed at random. It is a soft, elastic, and rubbery material
• D. None of these

Answer 1

Answer: (A)

all methyl groups are on one side of the extended chain. It is a highly crystalline, has high melting point and forms strong fibres

Isotactic, syndiotactic and atactic represent different types of polymers having a particular relative stereochemistry of adjacent chiral centers. In isotactic polymers, all the substituents are located on the same side of the macromolecular backbone. In syndiotactic polymers, the substituents have alternate positions along the backbone.
For atactic polymers, the substituents are placed randomly along the chain.
In case of polypropylene polymer, R group in figure below is a methyl group.