Which of the following elements belongs to the first inner transition series?

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

Which of the following properties decreases on moving from $Ce$ to $Lu$?

Name the members of the lanthanoid series which exhibit $+4$ oxidation state and those which exhibit $+2$ oxidation state. Try to correlate this type of behavior with the electronic configurations of these elements.

Which of the following elements belongs to the actinoid series?

The ionic radius of $La^{3+}$ is $1.06 \ \mathop{A}\limits^o$. Which of the following is the closest value for the ionic radius of $Lu^{3+}$ in $\mathop{A}\limits^o$? $(Lu = 71, La = 57)$