The species which can best serve as an initiator for the cationic polymerization is:

Neoprene (synthetic rubber) is a polymer of ........

The homopolymer formed from $4-$hydroxybutanoic acid is:

Which one of the following is a chain growth polymerisation?

Which of the following polymers can be prepared by condensation polymerization?

The polymer $X$ consists of linear molecules and is closely packed. It is prepared in the presence of triethylaluminium and titanium tetrachloride under low pressure. The polymer $X$ is -