Question

Two elements `X and Y` have following electronic configurations.
`X: 1s^(2) 2s^(2) 2p^(6) 3s^(2) 3p^(6) 4s^(2)`
`Y: 1s^(2) 2s^(2) 2p^(6) 3s^(2) 3p^(5)`
The expected compound formed by combination of X and Y will be expresed as
A. `XY_(2)`
B. `X_(5)Y_(2)`
C. `X_(2)Y_(5)`
D. `XY_(5)`

Answer 1

Correct Answer - a
Valency of element`X` is `2` (electrons in the outermost shell) while that of element `Y` is `1` (electron required in the outermost shell to complete octet). So, the formula of the compound between `X and Y` is `XY_(2)`