Study the reaction.

NH4+ + NO2– ⟶ N2 + 2H2O

The rate of this reaction is proportional to the concentration of ammonium (NH4+) and the concentration of nitrogen dioxide (NO2–).

What is the rate law of this reaction?

Rate = K[N2][H2O]2
Rate = K[NH4+]2
Rate = K[NH4+][NO2–]
Rate = K[NO2–]2