Chemistry - Mole Concept Question with Solution | TestHub

${\mathrm{Ca}}^{2+},{\mathrm{Cl}}^{-},{\mathrm{S}}^{2-}$ and ${\mathrm{K}}^{+}$are isoelctronic species. In isoelectronic ions, size decrease with increasing nuclear charge. Hence, ${\mathrm{Ca}}^{2+}$ ion is the smallest among these.