Question

The boiling point of a liquid increases when there is a _____________________
A. Decrease in atmospheric pressure
B. Increase in atmospheric pressure
C. No change in atmospheric pressure
D. Increase in mass of liquid

Answer 1

Hint: The liquid phase is converted to the gaseous phase when the vapour pressure of the liquid is equal to the atmospheric pressure of the liquid.


Step by step answer: Boiling is the process of conversion of liquid into the gaseous form when it is heated to its boiling point. Boiling takes place with the formation of bubbles which are formed when the atoms or the molecules of a liquid have sufficient energy to change temperature from a liquid state to the gaseous state.

Boiling is a physical change of nature in which the chemical properties of the liquid is not altered. The boiling point ofa liquid depends upon the temperature, atmospheric pressure and the vapour pressure of the liquid.

Liquid boils at a temperature when the vapour pressure is equal to the pressure of the gas above it. It clearly indicates that when the atmospheric pressure is lower the boiling point is also lower at which the liquid can start boiling. The boiling point increases with the increase in pressure to the critical point when the properties of gas and liquid become identical to each other.

Therefore the boiling point of a liquid increases with the increase in the atmospheric pressure. Hence, the correct option is (B).


Note: The Boiling point of a liquid is affected by the pressure exerted above a gas which is known as atmospheric pressure, the larger the pressure, the more energy is required by the liquid to boil which means elevation in the boiling point.