Question

Which of the following arrangements represents the increasing order (smallest to largest) of ionic radii of the given species $O^{2-}, S^{2-}, N^{3-}, P^{3-} ?$

• A. $O^{2-} < N^{3-} < S^{2-} < P^{3-}$
• B. $O^{2-} < P^{3-} < N^{3-} < S^{2-}$
• C. $N^{3-} < O^{2-} < P^{3-} < S^{2-}$
• D. $N^{3-} < S^{2-} < O^{2-} < P^{3-}$

Answer 1

Answer: (A)

For isoelectronic species ionic radii decreases as the charge on ion decreases. Further on moving down in a group ionic radii increases. Hence the correct order is
$O^{2-} < N^{3-} < S^{2-} < P^{3-}$