Step-by-step explanation:
In combustion reaction, a compound reacts with oxygen and results in the formation of carbondioxide and water.
For example, when propane reacts with oxygen it results in the formation of carbondioxide and water.
The reaction is as follows.
Also, when there is incomplete combustion of carbon then it results in the formation of carbon monoxide. This reaction is as follows.
Thus, we can conclude that the products of a combustion reaction do NOT include hydrogen.