Write the structure of monomers used for getting the following polymers: (i) Nylon-6,6 (ii) Glyptal (iii) Buna - S OR (i) Is $\left[\mathrm{CH}_2-\overset{\mathrm{CH}_3}{\overset{\vert}{\mathrm{CH}}}\right]_n$ a homopolymer or copolymer? Give reason. (ii) Write the monomers of the following polymer: (iii) What is the role of sulphur in vulcanization of rubber?