Answer:
Law of conservation of mass state that mass can neither be created nor be destroyed. Also chemical reaction of the sum is outlined in The Law Of Conservation of Matter.
Step-by-step explanation:
In a chemical reaction the sum of the masses of the products will be equal to the sum of the masses of the reactants. Thus a chemical reaction conserves the total mass. For this law to be valid the system where the reactions take place should be closed.
It has to be properly ensured that there is no transfer of energy or mass between the system and its outer environment. If that happens the sum of masses of products differs from that of the reactants due to the gain or loss of matter to surroundings.