Question

Assertion : The vapour pressure of a liquid decreases if some non volatile solute is dissolved in it.

Reason : The relative lowering of vapour pressure of a solution containing a nonvolatile solute is equal to the mole fraction of the solute in the solution.

(a) Both A and R are true and R is the correct explanation of A

(b) Both A and R are true but R is not correct explanation of A

(c) A is true but R is false

(d) A and R are false

Answer 1

Correct option (b) Both A and R are true but R is not correct explanation of A

Explanation:

On adding a non volatile solute in a liquid the vapour pressure decreases because some molecules of the solvent on the surface are replaced by the molecules of the solute.