A solution of KMnO4 on reduction yields either a colourless solution or a brown precipitate or a green solution depending on pH of the solution. What different stages of the reduction do these represent and how are they carried out?

NEETprep Answer: Oxidising behaviour of KMnO4 depends on pH of the solution.
In acidic medium (pH < 7)
MnO4- + 8H+ + 5e-  Mn2+    +    4H2O
In alkaline medium (pH > 7)
          MnO4- + e-  MnO42-
In neutral medium (pH = 7)
     MnO4- + 2H2O + 3e-        MnO2        +        4OH-
                                                                               (Brown ppt)