Chemistry - Complete d-block Question with Solution | TestHub

In aqueous solution the configuration of the ions are following $\begin{array}{rl}{\mathrm{Cr}}^{3+}(21)& =3d^{3}4s^0\Rightarrow t_{2g}{}^3{e}_g^0\\ {\mathrm{V}}^{3+}(20)& =3d^{2}4s^0\Rightarrow t_{28}{}^2{e}_g^0\\ {\mathrm{Tr}}^{3+}(19)& =3d^{1}4s^0\Rightarrow t_{28}{}^1{e}_g^0\\ {\mathrm{Mn}}^{3+}(22)& =3d^{4}4s^0\Rightarrow t_{2g}{}^4{e}_g^0\end{array}$ We know that half-filled and fully filled orbitals are more stable than partially filled orbitals. Hence among the given ions the only ${\mathrm{Cr}}^{3+}$ ion which occupies half-filled $t_{2g}$ orbitals. Caution Although ${\mathrm{Mn}}^{3+}$ ion has half-filled $t_{\text{s orbital }}$ but there is one more electron filled in $e_R$ orbital which reduces the stability.