Question

Clothes dry faster in summer than in monsoon days. Why?
(A) Because dry air is less humid
(B) Wet air is less humid
(C) Dry air is more humid
(D) None of these

Answer 1

Hint: The process involved in drying of clothes is evaporation. It’s a type of vaporization of a liquid which happens from the surface of a liquid into a gaseous phase which is not saturated with the evaporating substance and the clothes dry up as the water molecules evaporate from the surface of the cloth.

Complete step by step solution:
- When a wet cloth dries, it is because the liquid water that is on the cloth evaporates into water vapor and diffuses out into the air. On the molecular scale, the wetness of a cloth or any other object consists of a number of water molecules non-statically and loosely bonded to each other in liquid form, as well as bonded to the cloth.
- The process of drying of cloth or any other object consists of individual water molecules breaking free of their bonds to each other and to the object, and then getting out into the air. Thus the speed at which a wet cloth dries is hence determined by the net evaporation rate of the liquid water on the object.
- The drying rate of a cloth is mainly influenced by the concentration of the water molecules in the surrounding air. . Humidity is the concentration of water molecules in the air. For the process of fast drying, we want the surrounding air to have a low humidity or concentration of water molecules. The slower a cloth dries when more humid is the surrounding air.
- As we know, in monsoon time there is a lot of humidity in air as compared to dry air in summer. As a result, the clothes will dry faster in summer time than in monsoon time.

Therefore, the answer is option (A) because dry air is less humid

Note: Keep in mind that the drying rate of a cloth or a particular wet object is also influenced by the other factors such as the temperature of the liquid water on the object and the air flow rate. This means that the wet clothes hanging on a hot day will dry much quicker than wet clothes hanging on a cold day.