Solution:
Melting is when a solid substance changes into liquid on heating. The particles in the solid state gain energy to overcome the bonding forces holding them in place.
Boiling is when a liquid substance changes into gas or vapour rapidly on heating or increasing temperature. When vapour pressure is equal to the atmospheric pressure exerted on liquid, that point is called the boiling point.
Condensation is the process of changing a gas to liquid on cooling. It is the reverse of evaporation.
Freezing is the process of changing a liquid into a solid by cooling. For example, Freezing of water to ice.
