Which of the following is paramagnetic with bond order `0.5`?

Options

A. `O_2^(-)`
B. `H_2^(+)`
C. `B_2`
D. `N_2`

Answer

B

Explanation

Both `O_2^(-)` and `H_2^(+)` are paramagnetic having one unpaired electron each.
Bond order `(O_2^(-))=(10-1)/(2)=1.5`
Bond order `(H_2^(+))=(1-0)/(2)=0.5`
`B_2, N_2,` and `F_2` are all diamagnetic.