There are some species given below. (i)`O_(2)^(+)` (ii)`CO` (iii)`B_(2)` (iv)`O_(2)^(-)` (v)`NO^(+)` (vi)`He_(2)^(+)` (vii)`C_(2)^(2+)` (vii)` CN^(-)` (ix)` N_(2)^(-)`
total number of species which have fractional bond order.

Answer

`4`

Explanation

`to` molecular orbital configuration for upto 14 electrons
`sigma_(1s)ltoverset("*")(sigma_(1s))ltsigma_(2s)ltoverset("*")(sigma_(2s))ltpi_(2px)pi_(2py)ltsigma_(2px)ltoverset("*")(pi_(2px))=overset("*")(pi_(2py))ltoverset("*")(simga_(2px))`
For more than 14 electrons `sigma_(1s)ltoverset("*")(sigma_(1s))ltsigma_(2s)ltoverset("*")(sigma_(2s))ltpi_(2px)=pi_(2py))ltoverset("*")(pi_(2px))=overset("*")(pi_(2py))ltoverset("*")(pi_(2px))`
Bond order `=(1)/(2)` number of electron in [Bonding M.O.-Antibonding M.O.]