Which of the following statement is correct among the species `CN^(Θ),CO` and `NO^(o+)` .

Options

A. Isolelectronic and weak field ligands
B. Isolelectronic with three bond order
C. Bond order three and weak field ligands
D. Bond order two and pi-acceptor

Explanation

Each of the species is isoelectronic and has `14e^(-')s` which are distributed in `MO` s as
`(sigma1s^(2))(sigma^(**) 1s^(2))(sigma2s^(2))(sigma^(**)2s^(2))(pi 2p_(x)^(2),pi2py_(y)^(2))`
`(sigma2p_(z)^(2))` Hence `N_(b)=10,N_(a) = 4`
`BO = (10-4)/(2) =3`
Alternatively,total number of `e^(-')s =14`
Number of remaining `p e^(-')s = (14 -8) =6`
`N_(b) =6, N_(a) =0`
`BO = (1)/(2) (6-0) =3`
So, statement (b) is correct .