Suppose the elements X and Y combine to form two compounds `XY_(2)` and `X_(3)Y_(2)`. When 0.1 mol of `XY_(2)` weights 10g and 0.05 mol of `X_(3)Y_(2)` weights 9g, the atomic weights of X and Y are-

Options

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

Answer

A

Explanation

Let, the weight of X and Y is a and b. mole no of X
`=("weight")/("molecular mass")`
`therefore 0.1=(10)/(a+2b) or, a+2b=100` . . . [1]
mole no. of `X_(3)Y_(2)=("weight")/("molecular mass")`
`therefore 0.05=(9)/(3a+2b) or, 3a+2b=180` . . . [2]
From [1] and [2], a=40 and b=30.