The biodegradable polymer is

Structures of some common polymers are given. Which one is not correctly presented?

Give reason: Why is the molecular mass of a polymer always expressed as an average?

Identify the biodegradable polymer from the following.

$C_6H_6O$ (phenol) $\xrightarrow[\text{3}H_2\text{ (High temp and pressure)}]{Ni} (A)$ $\xrightarrow{Cu} (B)$ $\xrightarrow{NH_2OH} (C)$ $\xrightarrow{H^{+}} (D)$ $\xrightarrow{HO^{-}} (E)$
Product $(E)$ is

During the vulcanization of rubber,natural rubber is heated with sulphur and some other additive to: