C3H3 is the molecular formula of propane.
When it is burned with oxygen result in the production of CO2.
Reaction is given as follow
C3H8 + 5O2 ---> 3CO2 + 4H2O.
The balance equation shows that 1mole of propane reacts with 5mole of oxygen results in the formation of 3 mole of carbon dioxide and 4 mole of water.