If we burn wood if change into ashes ,the gas produced by the burnings of the wood are very light and that is why they fly
Thus we know that burning can reduce a mass of something but actually the mass remains the same , how does the mass remain the same ?
Law of conservation
There is a statement in chemistry that says that mass cannot be created or destroyed in a chemical reaction , for example Magnesium + oxygen = Magnisiumoxide
For a atomic representation of 2 magnesium and 2 oxygen , here is how it looks
Magnesium and magnesium plus 2 oxygen , 2Mg + 2Co2 = MgC02 + MgCo2
This reaction of magnesium and oxygen proves that there is no mass created or destroyed
Example - 2
Wood + oxygen gives out Carbon dioxide + Water vapor + Ash , If we burn wood and store them with the gas the mass will remain same . For example if you have 500 grams of wood and burn it , if you store the gas in a glass or beaker the result of the reaction will also weight 500 grams