Fill in the blanks in the equations and statements below.

Nitrogen and oxygen molecules dissociate on hot metal surfaces such as those found in car engines creating nitrogen and oxygen atoms which can recombine to form nitrogen monoxide.

N₂ + O₂  --> 

Nitrogen monoxide (a pollutant) is slowly oxidised to nitrogen dioxide (a pollutant) by oxygen, ozone and HO₂ radicals.

2NO + O₂  --> 

Nitrogen dioxide undergoes photolysis in the presence of sunlight creating highly reactive atoms.

NO₂ +  -->  NO +

These oxygen atoms react with oxygen molecules forming .

O + + M  -->  O₃ +

Ozone reacts with hydrocarbons (another pollutant) to form a complex mixture including aldehydes (a pollutant).

+ hydrocarbons  -->  complex mixture including aldehydes (RCHO)