Q. For dilute solution Raoult’s law states that
A) The relative lowering of vapour pressure is equal to mole fraction of solute
B) The lowering of vapour pressure is equal to the mole fraction of solute
C) The vapour pressure of the solution is equal to mole fraction of the solvent
D) The relative lowering of vapour pressure is proportional to amount of solute in solution
Explanation
(a)
According to Raoult’s law in a solution of a non-volatile solute, the the relative lowering in vapour pressure is always equal to the mole fraction of the solute.
$\frac{p - p_{s}}{p} = X_{A} = \ \frac{N_{A}}{N_{A} + N_{B}}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.