(i) Why `H_(2)` is a stable molecule, but `He_(2)` is not?
(ii) Write cannonicals of `ClO_(4)^(-)` ion.

Explanation

(i) `H_(2):(sigma_(1s))^(2),B.O=(1)/(2)(2-0)=1`
`He_(2):(sigma_(1s))^(2)(sigma_(1s)^(**)),B.O=(1)/(2)(2-2)=0`
as bond order is zero, `He_(2)` molecule has not existance.
(ii)