Question

Evaporation of material takes place

• A. above its boiling point
• B. above its melting point
• C. below its boiling point
• D. below its melting point

Answer 1

Answer: (B), (C), (D)

below its melting point

The explanation for correct option:

1. Evaporation is the process that takes place at the surface of the liquid and can happen at any temperature whereas boiling is taking place under specific conditions and is a bulk transformation.
2. The air molecules that collide with the surface provide energy to the water molecules.
3. If this energy is sufficient to change the phase of the water molecules, a phenomenon known as evaporation occurs.

Hence, options (B), (C), (D) are correct.

The explanation for incorrect option:

1. Evaporation is the process that takes place at the surface of the liquid and can happen at any temperature whereas boiling is taking place under specific conditions and is a bulk transformation.
2. When boiling takes place, the inter-molecular bonds in water are broken and not the bonds between hydrogen and oxygen atoms. This breakage of bonds can happen only at certain temperature. While in evaporation few molecules manage to escape from the surface to the air.
3. Evaporation is a surface phenomenon and when a liquid has reached its boiling point or is above the boiling point, the surface of the liquid breaks.
4. Thus, evaporation does not occur at or above the boiling point of a liquid.

Hence, option (A) is incorrect.