Which of the following is paramagnetic ?

Options

A. CO
B. `CO_(2)^(-)`
C. `CN^(-)`
D. `NO^(+)`

Answer

B

Explanation

`O_(2)^(-)rArrsigma 1s^(2)sigma^(**)1s^(2)sigma 2s^(2)sigma^(**)2s^(2)sigma2p_(z)^(2)(pi2p_(x)^(2)=pi2p_(y)^(2))`
`(pi^(**)2p_(x)^(2)=pi^(**)2p_(y)^(1))`
One unpaired electron present in `pi^(**)` abmo.