C6H6 is the chemical formula of benzene. It is a molecule comsisting of 6 carbon atoms and 6 hydogen atoms. When benzene undergoes combustion in air, the carbon and hydrogen atoms combine with the molecules of oxygen present in air to form carbon dioxide and water respectively.

Carbon reacts with oxygen to given carbon dioxide: C + O2 --> CO2 and hydrogen reacts with oxyhen to form water: 2H2 + O2 --> 2H2O

The balanced equation of the chemical reaction of the combustion of benzene in air is 2C6H6 + 15O2 --> 12CO2 + 6H2O