The dand fblock elements - Result Question 14
####14. For the four successive transition elements $(Cr$, $Mn, Fe$ and $Co$ ), the stability of +2 oxidation state will be there in which of the following order?
[2011]
(a) $Mn>Fe>Cr>Co$
(b) $Fe>Mn>Co>Cr$
(c) $Co>Mn>Fe>Cr$
(d) $Cr>Mn>Co>Fe$
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Solution:
- (a)
$ \begin{aligned} & Cr^{2+}=\begin{array}{|l|l|l|l|l} \hline & 1 & 1 & 1 & \\ \hline & 1 & 1 & & 1 \end{matrix} \\ & Mn^{2+}=\begin{array}{|l|l|l|l|l|} \hline & 1 & 1 & 1 & 1 \\ \hline \end{matrix} \\ & Fe^{2+}=\begin{array}{|l|l|l|l|l|} \hline 1 & 1 & 1 & 1 & 1 \\ \hline \end{matrix} \\ & Co^{2+}=\begin{array}{|l|l|l|l|l|} \hline 1 & 1 & 1 & 1 & 1 \\ \hline \end{matrix} \end{aligned} $
$Mn^{2+}$ is most stable due to half-filled configuration. Hence, only option (a) can be the correct answer.
