Answer: The total number of atoms of each element on both sides of the equation must be the same for every chemical equation.
Step-by-step explanation:
Law of conservation of matter states that matter can neither be created nor be destroyed but it can only be transformed from one form to another form.
This also means that total number of individual atoms on the reactant side must be equal to the total number of individual atoms on the product side.
Every balanced chemical equation follows law of conservation of matter.
For Example: Formation of water molecule from hydrogen and oxygen gas. The equation follows:

On reactant side:
Number of hydrogen atoms = 4
Number of oxygen atoms = 2
On product side:
Number of hydrogen atoms = 4
Number of oxygen atoms = 2
Hence, the total number of atoms of each element on both sides of the equation must be the same for every chemical equation.