Find the mole fraction of the solute if the vapour pressure of a dilute aqueous solution of glucose is 720 mm of Hg at 373 K.

1/19

$\frac{P^o - P_s}{P^o}$ = Mole fraction of solute

P^o = vapour pressure of water at 373 K is 760 mm

$\frac{760 - 720}{760}$ = Mole fraction of solute

Mole fraction of solute = $\frac{40}{760}$ = $\frac{1}{19}$