JEE Main 2021 — d and f Block Elements Question with Solution

The $+3$ oxidation state of lanthanide is most stable and therefore lanthanide in $+4$ oxidation state has strong tendency to gain ${\mathrm{e}}^{-}$ and converted into $+3$ and therefore act as strong oxidizing agent. $e.g. {\mathrm{Ce}}^{+4}$ And therefore ${\mathrm{CeO}}_2$ is used to oxidized alcohol aldehyde and ketones. Lanthanide in $+2$ oxidation state has strong tendency to loss ${\mathrm{e}}^{-}$ and converted into $+3$ oxidation state therefore act as strong reducing agent. $\therefore {\mathrm{EuSO}}_4$ act as strong reducing agent.