AIIMS 2018 Chemistry Electronic Configuration MCQ Question

To determine the spin magnetic moment ($\mu$) of the metal M in the +2 oxidation state, we first identify the number of unpaired electrons in its electronic configuration, which is 3d⁵ 4s². In this configuration, the 3d subshell has 5 electrons, all of which are unpaired, leading to $n = 5$. Using the formula $\mu = \sqrt{n(n+2)}$, we calculate $\mu = \sqrt{5(5+2)} = \sqrt{35} \approx 5.9$, indicating that option C (3.9) is incorrect. The other options (A, B, D) do not match the calculated value, as they either overestimate or underestimate the magnetic moment based on the number of unpaired electrons.