According to Dalton’s Law of partial pressures combined with Raoult's Law, for a binary ideal soluti — Solutions and Colligative Properties Chemistry Question

💡 Solution & Explanation

Option A is an incorrect formulation; the proper derivation is $\frac{1}{P_{total}} = \frac{Y_A P_B^0 + (1-Y_A) P_A^0}{P_A^0 P_B^0}$, which rearranges to $P_{total} = \frac{P_A^0 P_B^0}{P_A^0 - (P_A^0 - P_B^0)Y_A}$. Options B and C are standard textbook definitions of mole fraction in vapour phase. Option D is mathematically sound; it is a direct rearrangement of Konowaloff's ratio $\frac{Y_A}{Y_B} = \frac{P_A^0 X_A}{P_B^0 X_B}$ solving for $X_A$.