Q. The vapour pressure of two liquids P and Q are 80 and 60 torr, respectively. The total vapour pressure of solution obtained by mixing 3 moles of P and 2 moles of Q would be :
A) 144 torr
B) 288 torr
C) 14 torr
D) 72 torr
Explanation
[Solution from source] x_P = 3/5 and x_Q = 2/5. By Raoult's law P = (3/5)(80) + (2/5)(60) = 48 + 24 = 72 torr. 144 torr comes from using mole numbers instead of mole fractions. Answer (4).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.