To the uninformed spouter on burning wood. Your comment that "oxygen has no weight" is incorrect. Oxygen is actually heavier than carbon (16.0 vs 12.0) and when the carbon burns it attaches itself to two oxygen atoms and forms a CO2 molecule, weight 48.0. So the weight of the product is more than the weight carbon that you started with. And, yes, gasses have weight. And chemistry is real.