KEAM 2021 Physics and Chemistry Solved Paper

Disproportionation redox reaction involves simultaneous oxidation and reduction of atoms of same element from one oxidation state to two different oxidation states.
In this reaction, N of nitrogen dioxide is of +4 oxidation state but after the reaction, N is present in +3 and +5 oxidation state simultaneously. So, this reaction is an example of disproportionation redox reaction.