$A$ member of the Lanthanoid series which is well known to exhibit $+4$ oxidation state is

Assertion : Magnetic moment of $Dy^{3+}$ is highest among lanthanoids.
Reason : Orbital motion contributes to the magnetic moment.

The element californium belongs to the family of

What is the general formula of lanthanoid hydroxide? (Consider $Ln$ as any lanthanoid element)

Which among the following lanthanoids has the smallest atomic size?

Identify the correct statements from the following :
$I$. The ionic radius of $Pr^{3+}, Dy^{3+}$ and $Sm^{3+}$ follow the order,$Sm^{3+} > Pr^{3+} > Dy^{3+}$.
$II$. $Eu^{2+}$ acts as a strong reducing agent.
$III$. $Pu$ exhibits $+7$ oxidation state.