What is evaporation of Water?

A.It is a process during which neither heat is absorbed nor evolved

B.It is a process accompanied by chemical reaction

C.exothermic process

D.endothermic process

 

The correct option is D. Endothermic process.

Complete step-by-step solution –

1. Definition of Evaporation:

Evaporation of water is the process in which liquid water changes into water vapour (gas) at temperatures below the boiling point.

It usually happens from the surface of the liquid when exposed to air.

2. Role of Heat:

For evaporation to occur, water molecules must gain enough kinetic energy to overcome the intermolecular forces that hold them together in liquid form.

This energy is absorbed from the surroundings in the form of heat.

3. Why Endothermic?

Since the process absorbs heat from the surroundings, it is called an endothermic process.

That is why evaporation causes cooling. For example:

Sweat evaporates from our skin by taking heat from the body, which makes us feel cool.

Water kept in an earthen pot stays cool because water seeps out and evaporates, taking heat away.

4. Incorrect Options Explained:

A. Neither heat absorbed nor evolved: Wrong, because heat is definitely absorbed.

B. Accompanied by chemical reaction: Wrong, evaporation is a physical change, not chemical.

C. Exothermic process: Wrong, because exothermic means heat is released, which is not the case here.

Factors that affect the rate of evaporation:

1. Surface area – larger area, faster evaporation.

2. Temperature – higher temperature, faster evaporation.

3. Humidity – lower humidity, faster evaporation.

4. Wind speed – higher speed, faster evaporation.

Evaporation is a natural cooling process and an important part of the water cycle, helping in cloud formation and rainfall.