The correct nond order for ` CO` and ` CO^+` are respectively :

Options

A. ` 3, 5//2`
B. ` 3,2 `
C. ` 3,7//2`
D. ` 4//2, 3`

Answer

C

Explanation

M.O. configuration of ` CO:`
`sigma1s^2 , sigma^(** )1s^2, sigma^2, sigma2p_x^2,[(pi2p_y^2),(pi2p_x^2)] sigma^(**) 2s^2`
M.O. configuration of `CO^+`
`sigma1s^2 , sigma^(**) 1s^2, sigma^2, sigma2p_x^2,[(pi2p_y^2),(pi2p_x^2)] sigma^(**) 2s^1`
Note that : bnond length of `CO^+` is shorter than `CO` and thus bond order should be greater for `CO^+` Also this will bot be possible if `CO` is supposed to have `M.O` configration : `sigma 1s^2 , sigma^(**) 1s^2 , sigma2s^2`.
`sigma^(**) 2s^2 , sigma2p_x^2, [(pi 2p_y^2),(pi 2p_z^2)]`.
This that : bond length of `CO^+` is shorter than `CO` and thus bond order should be greater for `CO^+` to `3` and ` 5//2` . The problem have been explained by concluding that 2s-orbital of oxygen has lower energy thabn 2-srobital of carbon . Thus on mixing ` sigma 2^(**)` attatins so high energy that it goes up ` sigma2p_x` as well as ` pi 2 p_x` and ` pi2p_y ` level .