Two liquids 'A' and 'B' form an ideal solution. At 300 K, the vapour pressure of a solution containing 1 mole of 'A' and 3 moles of 'B' is 550 mm Hg. At the same temperature, if one more mole of 'B' is added to the solution, the vapour pressure of solution increases to 560 mm Hg. Then the ratio of vapour pressures of A and B in their pure state is
Show Hint
For problems involving ideal solutions and Raoult's Law with two different compositions, you will always get a system of two linear equations. Set up the equations $P_{T1} = X_{A1}P_A^\circ + X_{B1}P_B^\circ$ and $P_{T2} = X_{A2}P_A^\circ + X_{B2}P_B^\circ$ and solve for the pure component vapour pressures.