Question

Which of the following contains maximum ionic radius?

• A. $C^{4-}$
• B. $N^{3-}$
• C. $O^{2-}$
• D. $M{g}^{2+}$

Answer 1

Answer: (A)

These all are isoelectronic species. Greater the nuclear charge stronger is the attraction for same number of electrons and smaller is the ion. Thus, nuclear charge on $C^{4-},N^{3-}$ and $O^{2-}$ is 6, 7 and 8 respectively but nuclear charge on $M{g}^{2+}$ is 12. Hence, $C^{4-}$ has larger ionic radius than $N^{3-},O^{2-}$ and $M{g}^{2+}$ .