Statement I is incorrect: $Cr^{2+}$ acts as a strong reducing agent because losing an electron oxidises it to $Cr^{3+}$, which has a highly stable half-filled $t_{2g}^3$ configuration. On the other hand, $Mn^{3+}$ acts as a strong oxidising agent because accepting an electron reduces it to $Mn^{2+}$, which has a highly stable half-filled $d^5$ configuration . Statement II is correct: Scandium in its +3 oxidation state ($Sc^{3+}$) has a $3d^0$ electronic configuration. Since it has zero unpaired electrons, it is diamagnetic. Diamagnetic substances are repelled by an applied magnetic field .