Question

In which of the following Lanthanoids oxidation state $+2$ is most stable?

• A. Ce
• B. Eu
• C. Tb
• D. Dy

Answer 1

Answer: (B)

Eu

Electronic configuration of Europium is $4f^{7}6s^2$. Hence the +2 state is most stable for Eu. As this leads to a half filled electronic shell, this state would be stable.