Which is natural source of oxides of nitrogen?
A natural source of nitrogen oxides occurs from a lightning stroke. The very high temperature in the vicinity of a lightning bolt causes the gases oxygen and nitrogen in the air to react to form nitric oxide.
N2+O2⟶NO
The nitric oxide very quickly reacts with more oxygen to form nitrogen dioxide.
NO+O2⟶NO2
Both of the nitrogen compounds are known collectively as nitrogen oxides or NOx.