AIIMS 2019 Chemistry Oxidation States MCQ Question

In the complex [Ni(CO)₄], nickel (Ni) has an oxidation state of 0, as calculated by the equation x + 4(0) = 0, where x represents the oxidation state of Ni and CO is a neutral ligand contributing 0 charge. The presence of the strong field ligand CO leads to the pairing of electrons in the 3d subshell, resulting in a low-spin configuration of [Ar]₃d⁹4s⁰, which is consistent with Ni in the zero oxidation state. Other options are not applicable as they do not provide relevant information or alternative answers to the oxidation state of Ni in this context.