In cationic polymerisation, carbocations are formed. Greater the stability of the carbocation, more reactive is the alkene. Since the stability of the intermediate carbocation follows the order :
$$C{H_3} - \mathop C\limits^ + H{C_6}{H_5} > C{H_3}\mathop C\limits^ + HC{H_3}$$       $$ > C{H_3}\mathop C\limits^ + HCl > C{H_3}\mathop C\limits^ + HCOOC{H_3}$$
therefore, reactivity decreases in the same order. Thus, styrene is most reactive.

Phenol and formaldehyde undergo condensation polymerisation under two different conditions to give a cross linked polymer called bakelite.

The repeating structural unit is $$ - C{H_2} - C{\left( {C{H_3}} \right)_2} - $$     and hence the monomer is $$iso$$  - butylene,

Glyptal is used in manufacture of paints and lacquers.

Polymerisation starts either by condensation or by addition reactions between monomers

Nylon – 6, 6 is a fibre with hydrogen bonds thus have strongest intermolecular forces. Buna - $$S$$  is a elastomer whereas polythene is thermoplastic. the intermolecular forces of attraction in thermoplastics is intermediate between elastomer and fibres. Therefore forces in elastomers are weakest.

All the given statements about fibres are correct.

The condensation polymerisation of hexamethylene diamine and adipic acid is done in solution form by interface technique. In this, liquid nylon polymer is obtained.