Question

Assertion: Bakelite is a thermosetting polymer.
Reason: It can be melted again and again without any change.

• A. A is incorrect but R is correct.
• B. A is correct but R is incorrect.
• C. Both A and R are correct but R is not the correct explanation of the A.
• D. Both A and R are correct and R is the correct explanation of the A.

Answer 1

The correct option is B A is correct but R is incorrect.

Bakelite is also called phenol formaldehyde resin. It is obtained by elimination reaction between phenol and formaldehyde.

Bakelite contains cross links, or heavily branched polymer chains. Bakelite polymer, upon heating is hardened and cannot be softened again.
Hence, it is a thermosetting polymer. Hence, the assertion is correct.
When bakelite is heated, the degree of cross linking significantly increases. So the polymer mass becomes infusible. It is not possible to get back the original shape after melting. Hence, it cannot be reused.
Hence, the bakelite polymer cannot be melted again and again without any change.
Hence, the reason is incorrect.
Option (c) is correct