Suppose elements X and Y combine to form two compounds XY2 and X3Y2. When 0.1 mol of XY2 weighs 10g and 0.05 mol of X3Y2 weighs 9g, the atomic weights of X and Y are (NEET 2016)

Given, 0.1 moles of 2 XY weighs 10 grams then 1 mole of 2 XY weighs 100 grams ------(1) 0.05 moles of 3 2 X Y weighs 9 grams then 1 mole of 3 2 X Y weighs 180 grams -----(2) Let, the atomic weight of element X and Y is x and y respectively Then, 2 100 x y ------(3) 3 2 180 x y ----(4) Subtracting equation 3 from 4, we get 2 80 80 40 2 x x Then, put x = 40 in equation 3 to get y 40 2 100 2 60 60 30 2 y y y Therefore, the atomic weights of X and Y are 40 grams and 30 grams respectively.