The most common oxidation states of manganese are +2, +3, +4, +6, and +7, though all oxidation. Compounds with oxidation states +5 (blue) and +6 (green) are strong oxidizing age...
read this....as Manganese undergoes disproportionation when acidic hydrolysed as it is unstable and changes to MnO2( +4 O.S) and MnO4- (+7 0.S) from Mn V compound