Question

The following are some statements about vapour pressure.

I. Vapour pressure of a solution increases with increase in temperature.

II. Liquids with high vapour pressure even at ordinary temperatures are volatile liquids.

III. The temperature at which vapour pressure of solution is equal to atmospheric pressure is called boiling point.

IV. When a non-volatile solute is dissolved in a volatile solvent, its vapour pressure decreases.

Which of the above is/are correct?

• A. All are correct
• B. II, III and IV
• C. I and II
• D. II and IV

Answer 1

The correct option is A All are correct

Vapour pressure of any substance increases non-linearly with temperature according to Clausius-Clapeyron relation.
The atmospheric pressure boiling point of a liquid is the temperature at which vapour pressure equals to ambient atmospheric pressure.

A substance with a high vapour pressure at normal temperature is often referred to volatile and also the vapour pressure of a solvent is lowered by the addition of non-volatile solute to form a solution.

Hence, all statements are correct.