DIRECTIONS : These are Assertion-Reason type questions. Each of these question contains two statements:Statement-1 (Assertion) and Statement-2 (Reason). Answer these question from the following four options.

Statement-1 : Bakelite is a thermosetting polymer.
Statement-2 : Bakelite can be melted again and again without any change.

Statement-1 is true, Statement-2 is true, Statement-2 is a correct explanation for Statement -1
Statement-1 is true, Statement-2 is true ; Statement-2 is NOT a correct explanation for Statement-1
Statement-1 is true, Statement-2 is false
Statement-1 is false, Statement-2 is true

Solution

Bakelite can be heated only once.

Statement-1 :In vulcanisation of rubber, sulphur cross links are introduced.
Statement-2 : Vulcanisation is a free radical initiated chain reaction.

Statement-1 is true, Statement-2 is true, Statement-2 is a correct explanation for Statement -1
Statement-1 is true, Statement-2 is true ; Statement-2 is NOT a correct explanation for Statement-1
Statement-1 is true, Statement-2 is false
Statement-1 is false, Statement-2 is true

Solution

Vulcanisation is a process of treating natural rubber with sulphur or some compounds of sulphur under heat so as to modify its properties. This cross-linking give mechanical strength to the rubber.

Among cellulose, poly (vinyl chloride), nylon and natural rubber, the polymer in which the intermolecular force of attraction is weakest is

nylon
poly (vinyl chloride)
cellulose
natural Rubber

Solution

Nylon and cellulose, both have intermolecular hydrogen bonding, polyvinyl chloride has dipole-dipole interactions, while natural rubber has van der Waal forces which are weakest.

The polymer containing strong intermolecular forces e.g.hydrogen bonding, is