State law of conservation of mass and explain how it is used while balancing a chemical equation ?

Answer :

according to Law of conservation mass "mass can neither be created nor be destroyed it can be changed one form to another. " In a chemical reaction reactants of certain masses react each other to form product of same mass as that of reactants it is due to the law of conservation of mass. A chemical equation can be balanced by balancing the number of elements on both product side as well as reactant side. By balancing the number of elements automatically the mass will be balanced.