Question

The common oxidation state shown by Europium in their compounds is:

• A. 1
• B. 3
• C. 5
• D. 6

Answer 1

The correct option is B 3

$\left[Xe\right]{4f}^n{6s}^2$ is the general configuration of Lanthanoids,it may seem $+2$ should be the common oxidation state but relative stability depends on other factors as well,Landthanoids most commonly shows $+3$ oxidation state due to high hydration enthalpy than of $+2$ oxidation state.

Europium being a member of lanthanoid series,also shows $+3$ oxidation state.