The correct option is B law of conservation of mass
In a balanced chemical equation, the number of atoms of each element is the same on both sides of the equation. This is in accordance with the law of conservation of mass.
According to this law, mass can neither be created nor be destroyed in a chemical reaction.
For example, consider the following balanced chemical equation
N2(g)+3H2(g)→2NH3(g)
28 g 6 g 34 g
Total mass of reactants = 28 + 6 = 34 g
Thus, the mass of the product is equal to the total mass of the reactants.