Question

In which of the following pairs, the ions are iso-electronic?
(i) Na^+, Mg^2+
(ii) Al^3+ , O^–
(iii) Na^+, O^2–
(iv) N^3–, Cl^–

Answer 1

(i)Na^+, Mg^2+ 
Same electronic configuration and same no. of electrons

Answer 2

Na^+, Mg^2+ (i) ions are iso-electronic