Which of the following specific sets correctly represents a strictly isoelectronic series?

Question

Professor PC Thomas Classes · Answer

(a) : Isoelectronic species are atoms or ions that have the exact same number of total electrons. $\mathrm{N}^{3-}$ has $7+3=10$ electrons. $\mathrm{O}^{2-}$ has $8+2=10$ electrons. $\mathrm{F}^{-}$ has $9+1=10$ electrons. $\mathrm{Na}^{+}$ has $11-1=10$ electrons. Since all of them possess exactly 10 electrons, they form a pure isoelectronic series.