Reduction of the metal centre in aqueous permanganate ion involves

The chemical formula of permanganate ion $Mn{O}_4^{-}$

The chemical reactions in different medium are as follows

$\begin{array}{l}Mn{O}_4^{-}+8H^{+}+5e^{-}\to M{n}^{+2}+2H_{2}O\left(acidic\right)\\ Mn{O}_4^{-}+2H_{2}O+2e^{-}\to Mn{O}_4^{-2}+4O{H}^{-}\left(neutral\right)\\ Mn{O}_4^{-}+e^{-}\to Mn{O}_4^{-2}\left(basic\right)\end{array}$

Therefore we can conclude from the balanced chemical equations that the number of electrons got exchanged in acidic, neutral and alkaline mediums are 5,3 and 1 respectively.