Question

In which of the following processes, change in the state of matter involves gaining of heat?

• A. Boiling
• B. Freezing
• C. Condensation
• D. Melting

Answer 1

Answer: (A), (D)

The correct options are
A Boiling
D Melting

$\bullet$ When a substance changes its state from liquid to gas on heating, it is said to be boiling and when a substance changes its state from solid to liquid on heating, it is said to be melting.
$\bullet$ When a substance changes its state from gas to liquid on cooling, the process is called condensation also when a substance changes its state from liquid to solid on cooling, the process is called freezing.

So, freezing and condensation involve loss of heat whereas boiling and melting involve the gain of heat.