Question

When a solid goes directly to a gas, which process amongst the following processes best describe the phase change?
(a) Sublimation
(b) Vaporization
(c) Condensation
(d) Deposition
(e) Melting

Answer 1

Hint: In this question think of the process that naphthalene balls undergo as when naphthalene balls are exposed to an external environment then it directly goes from solid form to gaseous state. This approach will help getting the right option.

Complete Step-by-Step solution:

The change of state is shown in the above diagram.
When solid goes into liquid it is called fusion or melting.
When liquid goes into vapor (gas) it is called vaporization.
And when solid goes directly into vapor (gas) it is called sublimation.
So this is the required answer.
Hence option (A) is the correct answer.

Note – Sublimation is a type of phase transition or a change in a state of matter, just like melting, freezing and evaporation. Through sublimation a substance goes from the solid state directly into the gaseous state without ever passing through a liquid phase. Another example of substances undergoing such change is dry ice or solid $C{O_2}$.