Question

If Raoult's law is obeyed, then vapour pressure of the solvent in a solution is directly proportional to:

• A. mole fraction of the solvent
• B. mole fraction of the solute
• C. mole fraction of the solvent and solute
• D. the volume of the solution

Answer 1

The correct option is A mole fraction of the solvent

According to Raoult's law; the partial vapour pressure of each component of an ideal mixture of liquids is equal to the vapour pressure of the pure component multiplied by its mole fraction in the mixture.

For solvent:

$P=P_A^o{X}_A$ ; $A\to$ solvent

$P\propto X_A$

Hence, the correct option is $A$.