Question

Lanthanide for which +II and +III oxidation states are common is:

• A. $La$
• B. $Nd$
• C. $Ce$
• D. $Eu$

Answer 1

The correct option is D $Eu$

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 $4f$ sub shell.
Due to stable half filled configuration $Eu$ shows $+2$ configuration.
${}^{63}Eu:\left[Xe\right]4f^{7}6s^2$