Question

what is meant by disproportion of an oxidation state

Answer 1

When a particular oxidation state becomes less stable relative to other oxidation states, one lower, one higher, it is said to undergo disproportionation. For example, manganese (VI) becomes unstable relative to manganese(VII) and manganese (IV) in acidic solution. 

3MnMO2−4+4H+→2MnO−4+MnO2+2H2O

Answer 2

When a particular oxidation state becomes less stable relative to other oxidation states, one lower, one higher it is said to undergo disproportionation. For example, manganese (VI) becomes unstable relative to manganese(Vll) and manganese(IV) in acidic solution.