Question

From the following pairs of ions which one is not an iso-electronic pair ?

• A. $O^{2-},F^{-}$
• B. $N{a}^{+},M{g}^{2+}$
• C. $M{n}^{2+},F{e}^{3+}$
• D. $F{e}^{2+},M{n}^{2+}$

Answer 1

The correct option is D $F{e}^{2+},M{n}^{2+}$

Isoelectronic refers to two atoms, ions, or molecules that have the same number of total electrons and the same number of valence electrons.
(a) $O^{2-}and{F}^{-}$ both have 10 electrons
(b) $N{a}^{+}andM{g}^{2+}$ both have 10 electrons
(c) $M{n}^{2+}andF{e}^{3+}$ both have 23 electrons
(d) $F{e}^{2+}$ has 24 electrons.
$M{n}^{2+}$ has 23 electrons.
So, option (d) is correct.