Which of the following is paramagnetic-

Options

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

Answer

D

Explanation

MO electronic configuration of `O_(2)^(-)(17)`:
`K K(sigma_(2s))^(2)(sigma_(2s)^(**))^(2)(sigma_(2p_(z)))^(2)(pi_(2p_(x)))^(2)(pi2_(p_(y)))^(2)(pi_(2p_(x))^(**))^(2)(pi_(2p_(y))^(**))^(1)`
Owing to the presence of one unpaired electron, it is paramagnetic in nature.