Question

In which of the following species, the colour is due to charge transfer?
$\left(I\right)$ ${\left[Mn{\left(OH\right)}_2\right]}^{2-}$ $\left(II\right)$ ${MnO}_4^{2-}$ $\left(III\right)$ ${MnO}_2$ $\left(IV\right)$ ${KMnO}_4$

• A. $I,II,III$ correct
• B. $II,IV$ correct
• C. $I,III$ correct
• D. only $IV$ correct

Answer 1

The correct option is D only $IV$ correct

The deep purple colour of potassium permanganate is due to charge transfer from oxygen to $Mn$. One of the oxygen becomes $O^{-}$ and the oxidation state of $Mn\left(VII\right)$ changes to $Mn\left(VI\right)$. $Mn\left(VI\right)$ has one unpaired $3d$ electron. This results in colour.