In any chemical reaction, the total mass of products is always equal to that of the reactants. This Is statement of the law of

The law of conservation of matter (also called conservation of mass) states that matter cannot be created or destroyed in a chemical reaction. The total mass of all the reactants before the reaction equals the total mass of all the products after the reaction.

This law was established by Antoine Lavoisier in the late 1700s. He carefully weighed substances before and after reactions and found the total mass always stayed the same. For example, if 10 g of reactants enter a reaction, exactly 10 g of products will be formed.

The law of constant composition (also called definite proportions) is different. It says a pure compound always contains the same elements in the same proportion by mass, no matter how it is made. For example, water is always 11.1% hydrogen and 88.9% oxygen by mass.

The law of multiple proportions states that when two elements form more than one compound, the ratios of the masses of one element that combine with a fixed mass of the other are small whole numbers. Since the question specifically says “total mass of products equals total mass of reactants,” it describes conservation of matter.