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

Match List-$I$ (polymer) with List-$II$ (monomer/s) and select the correct option:
| List-$I$ (polymer) | List-$II$ (monomer/s) |
| :--- | :--- |
| $(A)$ Bakelite | $(I)$ $2$-Methyl-$1,3$-butadiene |
| $(B)$ Natural rubber | $(II)$ Glycine + Aminocaproic acid |
| $(C)$ Glyptal | $(III)$ Phenol + formaldehyde |
| $(D)$ Nylon $2$-Nylon $6$ | $(IV)$ Phthalic acid + ethylene glycol |

Which one of the following is used in the preparation of cellulose nitrate?

The repeating unit of $PCTFE$ is .........

Explain the difference between Buna $-N$ and Buna $-S$.

The polymer used for optical lenses is