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?

The pair of lanthanoid ions which are diamagnetic is

Identify the correct decreasing order of ionic radii of the following lanthanoids: $Ce^{3+}$,$Pm^{3+}$,$Sm^{3+}$,and $Gd^{3+}$.

Which of the following elements are included in the actinoid series?

If the ionic radius of $_{57}La^{3+}$ is $1.06 \ \mathring{A}$,then the ionic radius of $_{71}Lu^{3+}$ will be approximately close to which of the following values in $\mathring{A}$?

The number of elements from the following that do not belong to lanthanoids is:
$Eu, Cm, Er, Tb, Yb$ and $Lu$