JEE Main 2024 — d and f Block Elements Question with Solution

A reducing agent, or reductant, loses electrons and is oxidized in a chemical reaction. A reducing agent is typically in one of its lower possible oxidation states, and is known as the electron donor.

${\mathrm{Cr}}^{2+}$ is reducing as it configuration changes from ${\mathrm{d}}^4$ to ${\mathrm{d}}^3$ due to formation of ${\mathrm{Cr}}^{3+},$ which has half filled ${\mathrm{t}}_{2 \mathrm{g}}$ level, on other hand, the change ${\mathrm{Mn}}^{3+}$ to ${\mathrm{Mn}}^{2+}$ result half filled ${\mathrm{d}}^5$configuration which has extra stability.