Question

Which of the following ions is smallest in size?

• A. $C{l}^{-}$
• B. $N{a}^{+}$
• C. $M{g}^{2+}$
• D. $S^{2-}$

Answer 1

Answer: (C)

For isoelectronic species $(M{g}^{2+}$ and $N{a}^{+})$ size decrease with increase of nuclear charge. Thus $M{g}^{2+}$ is smallest in size.