Consider the following species
`CN^(-),CN^(-),NO and `CN`.
Which one of these will hqave the highest bond order ?

Options

A. `CN^(+)`
B. `CN^(-)`
C. NO
D. CN

Answer

B

Explanation

`NO (15e^(-)) : sigma (1s)^(2) , sigma^(**) (1s^(2)), sigma^(**) (1s)^(2) , sigma (2s)^(2)`,
` sigma^(**) (2s)^(2), sigma (2p_(z))^(2) , pi(2p_(x))^(2)`
`pi (2p_(y))^(2) . Pi^(**) (2p_(x))^(1) = pi^(**) (2p_(y))^(0)`
B.O. ` = (10 - 5)/(2) = 2.5 `
`CN^(-) (14 e^(-)) : sigma(1s)^(2), sigma^(**) (1s)^(2), sigma (2s)^(2)` ,
` sigma^(**) (2s)^(2) , pi (2p_(x))^(2) = pi (2p_(y))^(2) `
`sigma (2p_(z))^(2)`
B.O. ` = (10- 4)/(2) = 3 `
` CN (13 e^(-)) : sigma(1s)^(2), sigma^(**) (1s)^(2), sigma (2s)^(2)` ,
` sigma^(**) (2s)^(2) , pi (2p_(x))^(2) = pi (2p_(y))^(2) `
`sigma (2p_(z))^(1)`
B.O. `= (9-4)/(2) = 2.5 `
`CN (12 e^(-)) : sigma(1s)^(2), sigma^(**) (1s)^(2), sigma (2s)^(2)` ,
`sigma^(**) (2s)^(2) , pi (2p_(x))^(2) = pi (2p_(y))^(2) `
B.O. ` = (8 - 4)/(2) = 2 `
Hence , `CN^(-)` has the highest bond order .