Q. The vapour pressure of a pure liquid A is 40 mm Hg at 310 K. The vapour pressure of this liquid in a solution with liquid B is 32 mm Hg. What is the mole fraction of A in the solution if it obeys the Raoult’s law?
A) 0.5
B) 0.6
C) 0.7
D) 0.8
Explanation
(d)
According to Raoult’s law,
$P_{A} = P_{A}^{\circ}\ ϰ_{A}$
or $ϰ_{A} = \frac{P_{A}}{P_{A}^{\circ}}$
=$\frac{32mm\ Hg}{40\ mm\ Hg} = 0.8$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.