Question

Salt can be separated from its solution (salt dissolved in water), because:

• A. (a) Mixing of salt in water is a change that can be reversed by heating and melting of salt.
• B. Mixing of salt in water is a change that cannot be reversed.
• C. Mixing of salt in water is a permanent change.
• D. Mixing of salt in water is a change that can be reversed by evaporation.

Answer 1

The correct option is D

Mixing of salt in water is a change that can be reversed by evaporation.

Explanation for correct option:

Option D

Evaporation:

• Salt can be separated from its solution because the mixing of salt in water is a change that can be reversed by evaporation.
• Evaporation is the process of changing a liquid into its vapor state by the action of heat.
• The process of evaporation can be made faster by heating.
• The process of evaporation is used on a large scale to obtain common salt from seawater.
• Sea water is trapped in shallow ponds and allowed to evaporate in the sun.
• Mixing of salt in water is a reversible change.

Reversible changes:

• Any changes which can be reversed or are a temporary conversion are known as reversible changes.
• Processes such as melting, boiling, evaporation, freezing, condensation, dissolution are reversible changes.
• For example, melting of wax, freezing of ice, boiling water which evaporates as steam and condenses back to the water.

Therefore, option D is correct.