JEE Main · 2021 · 31 Aug 2021 · Shift 1 · d and f Block Elements

A diamagnetic $+2$ ion must have every electron paired. Ytterbium, $Z=70$, gives $\mathrm{Y}{\mathrm{b}}^{2+}$ with the configuration $[\mathrm{Xe}]4f^{14}$, a completely filled $f$ subshell with no unpaired electrons. In the $+2$ state lanthanum, cerium and neodymium retain unpaired $d$ or $f$ electrons and are paramagnetic. The lanthanide that is diamagnetic in its $+2$ state is ytterbium.