Suppose the elements X and Y combine to form two compounds XY2 and X3Y2. When 0.1 mole of XY2 weights 10 g and 0.05 mole of X3Y2 weights 9 g, the atomic weights of X and Y are
30, 20
40, 30
60, 40
20, 30
Explanation:
For XY2 n = $\dfrac{w}{M}$
$0.1 = \dfrac{10}{X + 2Y}$
X + 2Y = 100 .......(1)
For X 3Y2 n = $\dfrac{w}{M}$
$0.05 = \dfrac{9}{3X + 2Y}$
3X + 2Y = 180 .......(2)
Form (1) and (2)
2X = 80
X = 40 and
2Y = 100 – 40 = 60
Y = 30