Which of the following is paramagnetic?

Options

(a) O₂⁻
(b) CN⁻
(c) NO⁺
(d) CO

Correct Answer:

O₂⁻

Explanation:

O₂⁻ (17) = σ1s², σ*1s², σ2s², σ*2s², σ2pₖ², π2pᵢ² = π2pⱼ², π*2pᵢ² = π*2pⱼ¹