The most basic oxide of lanthanoids is $:-$

Which of the following elements exhibits a $+4$ oxidation state?

Identify the incorrect statement from the following:

Provide the electronic configurations of lanthanoids $(4f)$ series elements $(Ln)$ and their ions $Ln^{2+}$ and $Ln^{3+}$,and state their characteristics.

What does lanthanoid contraction result in?

Use Hund's rule to derive the electronic configuration of $Ce^{3+}$ ion and calculate its magnetic moment on the basis of 'spin-only' formula.