MHTCET 25 Apr 2025 Shift 2 Paper

Concept:Spin only magnetic moment depends on the number of unpaired electrons present in the ion.Explanation:The spin only magnetic moment is given by $\mu = \sqrt{n(n+2)}$ BM, where $n$ is the number of unpaired electrons.So, greater the value of $n$, higher will be the magnetic moment.Now check the number of unpaired electrons for each ion.$\mathrm{Mn}^{2+}$: Electronic configuration is $3d^5$, so it has 5 unpaired electrons.$\mathrm{Ti}^{3+}$: Electronic configuration is $3d^1$, so it has 1 unpaired electron.$\mathrm{Cu}^{2+}$: Electronic configuration is $3d^9$, so it has 1 unpaired electron.$\mathrm{Ni}^{2+}$: Electronic configuration is $3d^8$, so it has 2 unpaired electrons.Hence, $\mathrm{Mn}^{2+}$ has the maximum number of unpaired electrons, $n = 5$.Therefore, $\mu = \sqrt{5(5+2)} = \sqrt{35} \approx 5.92$ BM, which is the highest among the given ions.Answer:$\mathrm{Mn}^{2+}$ (Option A)