JEE Main 2023 — D And F Block Elements Question with Solution

The reduction electrode potential of ${\mathrm{Mn}}^{3+}/{\mathrm{Mn}}^{2+}$ is $+1.57\mathrm{V}$ while that of ${\mathrm{Fe}}^{3+}/{\mathrm{Fe}}^{2+}$ is $+0.77\mathrm{V}$, hence $\mathrm{A}$ is wrong. Higher oxidation state of smaller $d$-block elements is stabilized (or say form compounds) with smaller anion oxide that can be explained by stearic reason hence $B$ is correct.

The oxidation electrode potential of ${\mathrm{Cr}}^{2+}/{\mathrm{Cr}}^{3+}$ is $+0.41\mathrm{V}$ hence it can reduce ${\mathrm{H}}^{+}$and so liberate ${\mathrm{H}}_2$. The unpaired electrons in ${\mathrm{V}}^{2+}$ are 3 hence the magnetic moment of ${\mathrm{V}}^{2+}$ will be lesser than 4.4 BM.

Hence, only $B$ and $C$ are correct.