What are transuranic elements?

Name a member of the lanthanoid series which is well known to exhibit $+4$ oxidation state.

$A$ lanthanoid has $n$ unpaired electrons and another lanthanoid has $(14-n)$ unpaired electrons. It means:

Which one of the following is the correct order of ionic radii?

Fill in the blanks given below:
$(i)$ Neptunium and Plutonium are obtained from ............ .
$(ii)$ Lanthanoid series and Actinoid series are known as ............ .
$(iii)$ The main energy level of an atom is called ............ .
$(iv)$ Elements that possess both metallic and non-metallic properties are called ............ .

What is the correct order of ionic radii for the $+3$ oxidation state in $Ce, La, Pm,$ and $Yb$?