Question

An ideal solution of two liquids A and B is placed in a cylinder containing piston. Piston is pulled out isothermally so that the volume of the liquid decreases but that of vapours increases. Negligibly small amount of liquid was left and mole fraction of A in vapour is 0.4. If P⁰A = 0.4 atm and P⁰B at the experimental temperature, which of the following is the total pressure at which the liquid is almost evaporated?

• (A) 0.334 atm
• (B) 0.667 atm
• (C) 1 atm
• (D) 2 atm

Answer 1

The Correct Option is B

Explanation:
$P_A=P_T{Y}_A$$P_A=P_A^{\circ }{X}_A$$\therefore P_T\times 0.4=0.4\times {\chi }_A$$P_T=X_A$Similarty, $P_T\times 0.6=1.2\times {\chi }_e$$x_A=2{\gamma }_B$$X_A+X_B=1$$P_T=P_A^{\prime }{X}_A+P_B^2{X}_0$