Q. From the following pairs of ions which one is not an iso-electronic pair?
A) $Na^+$, $Mg^{2+}$
B) $Mn^{2+}$, $Fe^{3+}$
C) $Fe^{2+}$, $Mn^{2+}$
D) $O^{2-}$, $F^-$
Explanation
[Solution] $Fe^{2+}$ has 24 electrons and $Mn^{2+}$ has 23, so they are not isoelectronic. Answer (3).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.