X2Y expresses molar ratio i.e Y=1.5 × 10 ^23 atomsSo X = 2(1.5 × 10^23) Therefore When mass of X is 80 gm . No. Of atoms is =3 × 10^23 atomsGram atomic weight is the weight 1 mole of X and 1 mole = 6 × 10^23 atoms By cross multiplication u will get atomic at as 160 grams