Question

Determine the correctness or otherwise of the following Assertion [p] and Reason [r].
[p]: The melting temperature of polyester (PET) fibres is higher than that of Nylon 6 fibres
[r]: The hydrogen bonding in PET is stronger than that in Nylon 6

• A. Both [p] and [r] are true and [r] is the correct reason for [p]
• B. Both [p] and [r] are true but [r] is not the correct reason for [p]
• C. Both [p] and [r] are false
• D. [p] is true but [r] is false

Hint:

While PET has stronger intermolecular forces and a more crystalline structure than Nylon 6, hydrogen bonding does not explain the difference in their melting points.

Answer 1

The Correct Option is D

Step 1: Melting Temperature of Polyester (PET) and Nylon 6. 
The statement [p] is true. The melting temperature of polyester (PET) fibres is indeed higher than that of Nylon 6. This is because PET has a more crystalline structure and stronger intermolecular forces compared to Nylon 6. 
Step 2: Hydrogen Bonding in PET and Nylon 6. 
The statement [r] is false. While both PET and Nylon 6 can form hydrogen bonds, it is the crystalline structure and rigidity of PET's polymer chains that contribute more significantly to its higher melting temperature, rather than hydrogen bonding. Nylon 6 does have hydrogen bonds, but this is not the primary reason for its lower melting point. 
Answer: (D)