Question

The process in which gas transform into solid is called:
(A) sublimation
(B) condensation
(C) evaporation
(D) deposition
(E) melting

Answer 1

Hint:. The phase transition is the necessary phenomenon in the chemistry and thermodynamics of any reaction. There are three states of matter and the six transitions are possible within those states i.e. melting, freezing, evaporating, condensing, sublimation, and deposition.

Complete step by step answer:
Let us study every phase transition in detail to answer the given question;
- Melting (also known as fusion)-
The transition from solid phase to liquid phase.
- Freezing-
The transition from liquid phase to solid phase.
- Evaporating-
The transition from liquid phase to gas phase.
- Condensing-
The transition from gas phase to liquid phase.
- Sublimation-
The transition from solid phase to gas phase (without passing through liquid phase).
- Deposition-
The transition from gas phase to solid phase (without passing through liquid phase).
Therefore, deposition is the process in which gas is transformed into solid.
So, the correct answer is “Option D”.

Additional information: Deposition is a thermodynamic process which is also known as desublimation as it is reverse of sublimation. It is an exothermic phase change as it releases energy. For example: soot deposition on the walls of the chimney.
- Sublimation is an endothermic process. The enthalpy of sublimation is the sum of enthalpy of fusion and enthalpy of evaporation.

Note: Some special conditions are required for a gas to transform directly to solid phase without passing through the liquid phase. During winter months, the transformation from water vapor to ice without becoming liquid is the well-known example to describe the process.