(a) PVC:
Monomer: Vinyl chloride `CH_(2)=underset(Cl)underset(|)(C)H`
(b) Melamine-formaldehyde polymer.
Monomer: (i) Formaldehyde HCHO
(ii)
(c) Buna-N:
Monomerr: (i) Butandiene `H_(2)C=CH-CH=CH_(2)`
(ii) Acrylnitrile `CH_(2)=underset(CN)underset(|)(C)H`