$4f^2$ electronic configuration is found in

Given below are two statements:
Statement $I$: $CeO_{2}$ can be used for the oxidation of aldehydes and ketones.
Statement $II$: Aqueous solution of $EuSO_{4}$ is a strong reducing agent.
In the light of the above statements,choose the correct answer from the options given below:

Which of the following statements is $NOT$ incorrect?

Which of the following lanthanoids shows $+4$ oxidation state to acquire noble gas configuration?
(At nos. : $La=57, Ce=58, Eu=63$ and $Yb=70$ )

Decrease in size from left to right in actinoid series is greater and more gradual than that in lanthanoid series due to:

The transition element ( $\approx 5 \%$ ) present with lanthanoid metal in misch metal is