A solution of A and B with 30 mol % A is in equilibrium with its vapour which contains 40 mol% % B. Assuming that the solution and the vapour behave ideally, calculate the ratio of vapour pressure of pure A and pure B.

Explanation

To solve the problem, we need to calculate the ratio of the vapor pressures of pure components A and B given the composition of the solution and the vapor phase. Here’s a step-by-step solution:

### Step 1: Determine the mole fractions in the solution
Given that the solution contains 30 mol% A, we can find the mole fraction of A (χA) and B (χB) in the solution.

\[ \chi_A = 0.30 \quad \text{(30 mol% A)} \]
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