Question

Dry ice is an example of-----process.

• A. evaporation
• B. crystallisation
• C. sublimation
• D. purification

Answer 1

The correct option is C

sublimation

Explanation for the correct option:
c) Sublimation:

• Sublimation: - The process of change of solid state directly to gaseous state without changing into liquid state or vice versa is called sublimation.
• Dry ice is solid carbon dioxide $\left({\mathrm{CO}}_2\right)$.
• On decreasing pressure to 1 atmosphere, dry ice (i.e., solid ${\mathrm{CO}}_2$)directly converts into a gaseous state without changing into a liquid state.
• Therefore, dry ice is an example of sublimation process.

Explanation for the incorrect options:

a) Evaporation:

The phenomenon of change of a liquid into vapour at any temperature below its boiling point is called evaporation.

b) Crystallization:

The process of formation of crystals from liquid substance is called crystallization.

d) Purification:

Purification is the process of removing unwanted impurities from a compound.

Hence, option (c) is correct. Dry ice is an example of sublimation process.