Define the coefficients for the reaction of oxidation and reduction by electron
balance method:
NaNO2 + KMnO4 + H2O
MnO2 + NaNO3 + KOH
Here is the balanced equation but let me point out that YOU should know how to do this. Tell me what you don't understand; perhaps I can get you stated on learning out to do it.
3NaNO2 + 2KMnO4 + H2O ==> 2MnO2 + 3NaNO3 + 2KOH