Question

Which of these does not help to speed up evaporation?

• A. increasing the surface area
• B. blowing air over the liquid surface
• C. increasing the temperature
• D. increasing the external pressure

Answer 1

The correct option is D

increasing the external pressure

Explanation for correct option:

Option (D):

1. If the pressure increases, the molecules will hardly reach the surface and the rate of evaporation decreases.
2. Ex: It is used in the natural cooling of water in earthen pots, natural drying of clothes, etc.

Explanation for incorrect option:

Option (A):

1. The process in which a liquid state transforms into a vapour state is called evaporation.
2. Only surface molecules take part in this phenomenon, that's why it is called a surface phenomenon.
3. As the surface area increase, evaporation also increases.

Option (B):

1. Blowing air over the liquid increase the rate of evaporation because it removes the vapour accumulated on the top of the liquid.

Option (C):

1. If the temperature increases, the rate of evaporation will also increase.

Hence, option (D) is correct option.