(i) In process A, a solid is changing into a liquid. Hence, A is melting or liquefaction or fusion.

The temperature at which a solid melts to become a liquid at the atmospheric pressure is called its melting point.

(ii) In process B, a liquid is changing into a gas. B is vaporization or evaporation.

The temperature at which a liquid starts boiling at the atmospheric pressure is known as its boiling point. Boiling is a bulk phenomenon. Particles from the bulk of the liquid gain enough energy to change into the vapour state.

(iii) In process C, a gas is changing into a liquid. C is condensation.

(iv) In process D, a liquid is changing into a solid. D is solidification.

(v) In process E, a solid is directly changing into a gas. E is sublimation.

(vi) In process F, a gas is changing directly into a solid. F is also sublimation.

The process of change of state of solid directly into a gas without changing into liquid state (or vice versa) is called sublimation.