The highest oxidation state in plutonium (At. No. = $94$) is

For the general electronic configuration $(n-2)f^{1-14}(n-1)d^{0-1}ns^2$,if $n=7$,the configuration belongs to which series?

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

Identify the ion having $4f^6$ electronic configuration.

Assertion : Ionisation enthalpies of the early actinoids are lower than for early lanthanoids.
Reason : $5f$ electrons are more effectively shielded from nuclear charge than $4f$ electrons.

Given below are two statements:
Statement $I$: In the Lanthanoids,the formation of $Ce^{+4}$ is favoured by its noble gas configuration.
Statement $II$: $Ce^{+4}$ is a strong oxidant reverting to the common $+3$ state.
In the light of the above statements,choose the most appropriate answer from the options given below: