Which statement is incorrect for the electronic configuration $[Xe]\, 4f^{7}\, 5d^{1}\, 6s^{2}$?

Identify all the correct statements for Lanthanide contraction.
$(A)$ The covalent properties of the Lanthanide metal hydroxides increase from $La$ to $Lu$.
$(B)$ The chemical reactivity decreases from $La$ to $Lu$.
$(C)$ $La(OH)_3$ is more basic than $Lu(OH)_3$.
$(D)$ $Zr$ and $Hf$ have about the same radius.
$(E)$ Separation of Lanthanides from one another is easy.

Most common oxidation states of $Ce$ $(cerium)$ are

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.

Which of the following elements are analogous to the lanthanides?

The correct order of atomic radii is