Solutions: JEE Main 2008 Chemistry question

At 80^oC, the vapour pressure of pure liquid ‘A’ is 520 mm Hg and that of pure liquid ‘B’ is 1000 mm Hg. If a mixture solution of ‘A’ and ‘B’ boils at 80^oC and 1 atm pressure, the amount of ‘A’ in the mixture is (1 atm = 760 mm Hg)