Question

If $P^{\circ }$ the vapour pressure of a pure solvent and $P$ is the vapour pressure of the solution prepared by dissolving a non volatile solute in it. The mole fraction of the solvent $x_A$ is given by:

• A. $\frac{P^{\circ }-P}{P^{\circ }}=x_A$
• B. $\frac{P^{\circ }-P}{P}=x_A$
• C. $\frac{P}{P^{\circ }}=x_A$
• D. $P^{\circ }-P=x_A$

Answer 1

The correct option is C $\frac{P}{P^{\circ }}=x_A$

$P^0$ the vapour pressure of a pure solvent and P is the vapour pressure of the solution prepared by dissolving a non volatile solute in it. The mole fraction of the solvent $x_A$ is given by:

$x_A=\frac{P}{P^0}$

So answer is C.