Question

Assertion :When methanol is added to water, boiling point of water increases. Reason: When a volatile solute is added to a volatile solvent, elevation in boiling point is observed.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Both Assertion and Reason are incorrect

Answer 1

The correct option is D Both Assertion and Reason are incorrect

Elevation of boiling-point describes that the boiling point of a liquid (a solvent) will be higher when another compound is added to it, meaning that a solution has a higher boiling point than a pure solvent.

This happens whenever a non-volatile solute, such as a salt, is added to a pure solvent, such as water.

When methanol is added to water, the boiling point of water decreases.
When a more volatile solute is added to the volatile solvent vapour pressure of solvent increases due to an elevation in boiling point colligative property.

Hence, option $D$ is correct.