Question

The statement(s) that are correct about the species O 2– , F – , Na+ and Mg2+.
(A) All are isoelectronic
(B) All have the same nuclear charge
(C) O2– has the largest ionic radii
(D) Mg2+ has the smallest ionic radii
Choose the most appropriate answer from the options given below :

• A. (B), (C) and (D) only
• B. (A), (B), (C) and (D)
• C. (C) and (D) only
• D. (A), (C) and (D) only

Answer 1

Answer: (D)

(A), (C) and (D) only

Answer 2

- $O^{2-}, F^-, Na^+, \text{ and } Mg^{2+}$ are isoelectronic (same number of electrons = 10).

- $O^{2-}$ has the largest ionic radius due to its lowest effective nuclear charge ($Z_{\text{eff}}$).

- $Mg^{2+}$ has the smallest ionic radius due to its highest effective nuclear charge.
Hence, statements (A), (C), and (D) are correct.