The $trans$-form of polyisoprene is:

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 polymer from the following is used as synthetic leather?

Assertion : Bakelite is a thermosetting polymer.
Reason : Bakelite can be melted again and again without any change.

Phenol and formaldehyde undergo condensation to give a polymer $(A)$ which on heating with formaldehyde gives a thermosetting polymer $(B)$. Name the polymers. Write the reactions involved in the formation of $(A)$. What is the structural difference between the two polymers?

The biodegradable polymer which can be produced from glycine and aminocaproic acid is