AIIMS 2019 Chemistry Electronic Configuration MCQ Question

In the molecular orbital configuration of O₂, the highest occupied molecular orbitals (HOMO) are the π2p orbitals, which are degenerate (equal in energy) and can accommodate one additional electron each. When forming O₂⁻, the added electron will occupy one of these π2p orbitals, specifically π2pₓ or π2pᵧ, leading to the correct representation as π2pₓ or π2pᵧ. Other options are incorrect because they do not accurately reflect the filling of the degenerate π* orbitals, which must follow Hund's rule, ensuring that each orbital is singly occupied before any pairing occurs.