Suppose the elements X and Y combine to form two compounds of `XY_(2) and X_(3)Y_(2)`. When 0.1 mole of `XY_(2)` weighs 10 g and 0.05 mole of `X_(3)Y_(2)` weighs 9 g , what are tha atomic masses of X and Y ?

Options

A. 30, 20
B. 40, 30
C. 60, 40
D. 20, 30

Answer

B

Explanation

For `XY_(2) " "n =(2)/(M)`
`0.1 = (10)/(X+2Y)`
`X + 2Y = 100" "……(i)`
For `X_(3)Y_(2) " " n = (w)/(M)`
`0.05 = (9)/(3X + 2Y)`
`3X + 2Y = 180`
From (i) and (ii) b
2X = 80
`X = 40` and `2Y = 100 - 40 `
= 60
Y = 30