Take a small piece of used paper. Weight it on an electronic balance which will be readily available in your nearby grocery shop. Burn the piece of paper and now weigh the ash. What do you observe about the initial and final weighs? What can you infer ?
Ans. Suppose the weight of small piece of used paper is 2 gms. After burning the piece of paper the weight of ash remains the same i.e. 2 gms.
So, we observe that the weight remains the same. This is due to law of conservation of mass.
The total mass of the reactant is equal to the total mass of the products
during a chemical reaction. Therefore chemical equation needs to be balanced.