Disproportionation reactions are redox reaction in which a compound undergoes oxidation as well as reduction. The element of reacting species is in an intermediate oxidation state and simultaneously gets oxidised and reduced. 3
+3
Cl
O2−→
−1
Cl−
+2
+5
Cl
O3−
0
Cl2
+OH−→
−1
Cl−
+
+5
ClO3−
+H2O 2Mn3++2H2O→Mn2++
+4
MnO2
+4H+ But MnO4− does not get disproportonated. Hence, option (c) is the correct answer.