Question

The relative lowering of the vapour pressure is equal to the ratio between the number of

(a) solute molecules to the solvent molecules

(b) solute molecules to the total molecules in the solution

(c) solvent molecules to the total molecules in the solution

(d) solvent molecules to the total number of ions of the solute.

Answer 1

Correct option (a) solute molecules to the solvent molecules

Explanation :

Here, P^o_A - P_A, (difference in vapour pressure of pure solvent and solution): lowering in vapour pressure......(i)

Now, P^o_A = vapour pressure of pure solvent ...(ii)

by dividing (i) and (ii).

which is relative lowering in vapour pressure