Question

The isoelectronic pair of ions is

• A. $Sc^{2+}$ and $V^{3+}$
• B. $Mn^{2+}$ and $Fe^{3+}$
• C. $Mn^{3+}$ and $Fe^{2+}$
• D. $Ni^{3+}$ and $Fe^{2+}$

Answer 1

Answer: (B)

The isoelectronic species are those species which have same number of electrons.
(a) $Sc^{2+}$ and $V^{3+}$
Number of electrons in $Sc^{2+} =19$
Number of electrons in $V^{3+} =21$
(b) $Mn^{2+}$ and $Fe^{3+}$
Number of electrons in $Mn^{2+} = 23$
Number of electrons in $Fe^{3+} =23$
(c) $Mn^{3+}$ and $Fe^{2+}$
Number of electrons in $Mn^{3+}=22$
Number of electrons in $Fe^{2+} =24$
(d) $Ni^{3-}$ and $Fe^{2-}$
Number of electrons in $Ni^{3-} = 31$
Number of electrons in $Fe^{2-} = 28$
Thus, $Mn^{2+}$ and $Fe^{3+}$ are isoelectronic pair