Question

When a liquid starts to boil its temperature remains constant.

• A. Increases
• B. Decreases

Answer 1

The correct option is A

Increases

As a liquid is heated, its temperature increases. As its temperature increases, the molecules of the liquid gain energy and their kinetic energy increases. As the kinetic energy increases, the molecular motion increases and the molecules of the liquid overcome the force of attraction between them.

The temperature remains constant during boiling of water even though heat is supplied constantly because all the heat energy provided is used up in changing the state of water from liquid to gaseous water vapour. Therefore all the heat energy provided help in overcoming the inter-particle force of attraction.

Hence when a liquid starts to boil its temperature remains constant.