Question

Lanthanide and actinides resemble in:

• A. electronic configuration
• B. oxidation state
• C. ionisation energy
• D. formation of complexes

Answer 1

The correct option is B oxidation state

Lanthanides show variable oxidation states. The most stable oxidation state of Lanthanides is $+3$. They also show $+2$ and $+4$ oxidation states due to the presence of either half-filled or completely filled or empty $4f$ subshell.

Unlike lanthanides, actinides show a variety of oxidation states from $+3$ to $+6$ due to the very small energy gap between $5f$, $6d$ and $7s$ subshells.

The principal oxidation states are $+3$ and $+4$. The $+3$ oxidation state is the most stable. The $+4$ oxidation state is the most stable in $Th$ and $Pu$. $+5$ in $Pa$ and $Np$ and $+6$ is seen in $U$. In actinides, the distributions of oxidation states are uneven.

Therefore, the correct answer is (B)