The disproportionation of $\mathrm{MnO}_{4}^{2-}$ in acidic medium resulted in the formation of two manganese compounds $\mathrm{A}$ and $\mathrm{B}$. If the oxidation state of $\mathrm{Mn}$ in $\mathrm{B}$ is smaller than that of A, then the spin-only magnetic moment $(\mu)$ value of B in BM is __________. (Nearest integer)
Answer (integer)
4
Solution
$3 \overset{+6}{\mathrm{MnO}_{4}^{-2}}+4 \mathrm{H}^{+} \rightarrow \overset{+4}{\mathrm{MnO}_{2}}+\overset{+7}{\mathrm{MnO}_{4}^{-}}$
<br/><br/>
$\mathrm{Mn} \rightarrow 4 s^{2} 3 d^{5}$
<br/><br/>
$\mathrm{Mn}^{+4} \rightarrow 3 d^{3}$
<br/><br/>
$\mathrm{n}=3$
<br/><br/>
$$
\begin{aligned}
\mu &=\sqrt{n(n+2)} \\\\
&=\sqrt{3(5)} \\\\
&=\sqrt{15} \\\\
&=3.87 \approx 4 \text { B.M. }
\end{aligned}
$$
About this question
Subject: Chemistry · Chapter: d and f Block Elements · Topic: Properties of Transition Metals
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