Which of the following sets of ions forms an isoelectronic series?

• A. Na^+, Mg^{2+}, Al^{3+}
• B. K^+, Ca^{2+}, Cl^-
• C. Li^+, Be^{2+}, B^{3+}
• D. O^{2-}, F^-, Ne

Answer: (A)

Verified step by step guidance

1. Understand that an isoelectronic series consists of ions or atoms that have the same number of electrons.
2. Determine the number of electrons in each ion by subtracting the charge from the atomic number (number of protons) of the neutral atom.
3. For example, for Na^+ (sodium ion), start with sodium's atomic number 11, then subtract 1 electron due to the +1 charge, resulting in 10 electrons.
4. Repeat this process for each ion in the given sets to find their electron counts.
5. Compare the electron counts within each set; the set where all ions have the same number of electrons forms the isoelectronic series.