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.

(N/A) The lanthanoids that exhibit $+2$ and $+4$ oxidation states are listed in the table below:

$+2$ Oxidation State	$+4$ Oxidation State
$Nd \ (60), Sm \ (62), Eu \ (63), Tm \ (69), Yb \ (70)$	$Ce \ (58), Pr \ (59), Nd \ (60), Tb \ (65), Dy \ (66)$

Correlation with electronic configuration:
$1$. $Ce^{4+}$ $([Xe] \ 4f^0)$ attains a stable noble gas configuration.
$2$. $Tb^{4+}$ $([Xe] \ 4f^7)$ attains a stable half-filled $f$-orbital configuration.
$3$. $Eu^{2+}$ $([Xe] \ 4f^7)$ attains a stable half-filled $f$-orbital configuration.
$4$. $Yb^{2+}$ $([Xe] \ 4f^{14})$ attains a stable fully-filled $f$-orbital configuration.