JEE Main · 2025 · 28 Jan 2025 · Shift 2 · d and f Block Elements

Among $M{n}_2{O}_3$, TiO and VO, $M{n}_2{O}_3$ is the strongest oxidising agent, consistent with the high standard reduction potential $E_{M{n}^{3+}/M{n}^{2+}}^{\circ }=+1.57V$. In $M{n}_2{O}_3$, manganese is present as $M{n}^{3+}$, configuration $[Ar]3d^4$, giving four unpaired electrons. The spin-only magnetic moment is $\mu =\sqrt{n(n+2)}=\sqrt{4\times 6}=\sqrt{24}=4.90B.M.$, which rounds to 5 B.M.