Which of the following compounds has colour but no unpaired electrons?
Which of the following compounds has colour but no unpaired electrons?
$\mathrm{KMnO}_{4}$
$\mathrm{K}_{2} \mathrm{MnO}_{4}$
$\mathrm{MnSO}_{4}$
$\mathrm{MnCl}_{2}$
Solution
Electronic configuration of $\mathrm{Mn}$ is $[\mathrm{Ar}] 3 d^{5} 4 s^{2}$. Being transition metal it has 7 valence electrons and all are involved in bond formation in $\mathrm{MnO}_{4}^{-}$. Hence it has no unpaired electron.
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