Question

Assertion: Liquid molecules have greater potential energy at the melting point.

Reason: Intermolecular spacing between molecules increases at melting point.

• A. If both assertion and reason are true and reason is the correct explanation of assertion
• B. If both assertion and reason are true but reason is not the correct explanation of assertion
• C. If assertion is true but reason is false
• D. If both assertion and reason are false

Answer 1

Answer: (A)

A

Answer 2

Assertion Analysis:

Melting is a phase transition from solid to liquid. During melting, heat (latent heat of fusion) is supplied at a constant temperature. This energy overcomes intermolecular forces, increasing the potential energy of the molecules. Thus, the Assertion is True.

Reason Analysis:

When a solid melts into a liquid, molecules gain more freedom, increasing the average distance between them. Thus, the Reason is True.

Relationship:

The increase in intermolecular spacing (Reason) implies work done against attractive forces, stored as increased potential energy (Assertion). Therefore, the Reason correctly explains the Assertion.