Liquids A and B form an ideal solution. A certain solution of A and B contains 25 mole per cent of A — Solutions and Colligative Properties Chemistry Question

💡 Solution & Explanation

Given $X_A = 0.25, X_B = 0.75$, and $Y_A = 0.50, Y_B = 0.50$. Since $Y_A/Y_B = \frac{P_A^\circ X_A}{P_B^\circ X_B}$, $1 = \frac{P_A^\circ \cdot 0.25}{P_B^\circ \cdot 0.75} \implies \frac{P_A^\circ}{P_B^\circ} = \frac{0.75}{0.25} = \frac{3}{1}$. Therefore, correct answer is B.