AIPMT PRELIMS2012Chemistry-Solutions

AIPMT PRELIMS 2012 Chemistry Raoult's Law MCQ Question

Type: MCQ-numerical-Medium-Class 12

Pₐ and P_b are the vapour pressures of pure liquid components A and B, respectively of an ideal binary solution. If xₐ represents the mole fraction of component A, the total pressure of the solution will be

A

P_b + xₐ (Pₐ − P_b)

B

Pₐ + xₐ (P_b − Pₐ)

C

Pₐ + xₐ (Pₐ − P_b)

D

P_b + xₐ (P_b − Pₐ)

Correct Answer

Option A

Detailed Explanation

The total pressure is given by Raoult's law: P_total = Pₐ · xₐ + P_b · x_b. Since x_b = 1 − xₐ, substituting gives the correct expression.

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