Which one is the correct structure of neoprene?

The compound required for the formation of a thermosetting polymer with methanol is

Which of the following are synthetic rubbers?
$(i)$ Terylene
$(ii)$ Buna$-S$
$(iii)$ Buna$-N$
$(iv)$ Neoprene
$(v)$ Polyacrylonitrile

The polydispersity index of a polymer containing $10$ molecules with molecular mass $1.0 \times 10^4$ and $10$ molecules with molecular mass $1.0 \times 10^5$ is approximately.

If $\bar{M}_w$ is the weight average molecular weight and $\bar{M}_n$ is the number average molecular weight of a polymer, the poly dispersity index $(PDI)$ of the polymer is given by

Which among the following polymers is used for making handles of cooker?