Question

Which of the following process/ processes release energy in the form of heat ?
(i) Condensation

(ii) Vaporization

(iii) Freezing

(iv) Melting

• A. Only (i)
• B. Only (iv)
• C. (i) and (iii)
• D. (ii) and (iv)

Answer 1

The correct option is C

(i) and (iii)

The explanation for correct option:
(C) (i) and (iii)

• Both condensation and freezing are accompanied by the release of energy, as a result, the kinetic energy of molecules decreases with a decrease in temperature.
• Condensation is the process where water vapour becomes liquid. It is the reverse of evaporation, where liquid water becomes a vapour.
• The kinetic energy of the molecules is defined as the average energy possessed by the molecule due to their motion which is directly proportional to the temperature.

The explanation for incorrect options:

(ii) Vaporization

• Vaporization can be defined as the process in which the liquid state changes into the vapour state. As a result of an increase in temperature, the kinetic energy of the molecules increases.
• Due to the increases in kinetic energy, the force of attraction between the molecules reduces.
• As a result, they escape into the surrounding in the form of vapors.
• This process involves the consumption of heat energy.
• Vaporization can be divided into two types. Evaporation & Boiling.
• Industrially, salt is recovered from sea-water by the process of vaporization.
• Wet clothes are dried up due to the process of vaporization.

(iv) Melting

• The process in which a substance changes from solid-state to a vapour state is referred to as melting.

Hence option C is correct.