Fuel A is a compound of carbon, hydrogen, and oxygen, while fuel B is a compound of carbon and hydrogen only. Which one of these will have a lower ignition temperature if both have the same number of carbon atoms in their molecules?
Definition of Ignition Temperature:
The ignition temperature is the minimum temperature at which the material will ignite without a spark or flame being present.
Thus, Fuel A will have a lower ignition temperature than fuel B because fuel A contains oxygen which lowers the ignition properties of the fuel.