Two elements, and , combine to form two binary compounds. in the first compound, 28.0 g of combines with 3.00 g of . in the second compound, 7.00 g of combines with 4.50 g of . show that these data are in accord with the law of multiple proportions. if the formula of the second compound is , what is the formula of the first compound?

)benzene and toluene form nearly ideal solutions. consider an equimolar solution of benzene and toluene. at 20 °c the vapour pressures of pure benzene and toluene are 9.9 kpa and 2.9 kpa, respectively. the solution is boiled by reducing the external pressure below the vapour pressure. calculate (i) the pressure when boiling begins, (ii) the composition of each component in the vapour, and (iii) the vapour pressure when only a few drops of liquid remain. assume that the rate of vaporization is low enough for the temperature to remain constant at 20 °c.