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

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

Which of the following elements can form compounds in $+3$ to $+7$ oxidation states?

The pair of lanthanoid ions which are diamagnetic is

Identify the correct actinide series from the following.

Find the atomic number of the element at which pairing in the $4f$ orbital starts.