If the electronic configuration of $M^{3+}$ is $[Xe] \ 4f^3$,then $M^{3+}$ is

What is the electronic configuration of $Ce$ $(Z = 58)$?

Consider the following statements:
$I$. $La(OH)_3$ is the least basic among hydroxides of lanthanides.
$II$. $Zr^{4+}$ and $Hf^{4+}$ possess almost the same ionic radii.
$III$. $Ce^{4+}$ can act as an oxidizing agent.
Which of the above is/are true?

What is the correct order of basic strength of the following metallic hydroxides?

Which of the following statements is $INCORRECT$?

Lanthanoids are