Which law states that matter cannot be created or destroyed in a chemical reaction?

The principle that matter cannot be created or destroyed during a chemical reaction is defined by the Law of Conservation of Mass. This law asserts that in a closed system, the total mass of reactants will always equal the total mass of products. Hence, no matter is lost or gained; it simply changes forms.

This concept is fundamental to understanding chemical reactions, as it confirms that all atoms present in the reactants are accounted for in the products, merely rearranged to form new substances. Hence, any chemical equation must balance in terms of the number of atoms of each element.

In contrast, the other options focus on different aspects of chemistry. The Law of Definite Proportions concerns the fact that a chemical compound contains the same elements in exactly the same proportions by mass, regardless of the sample size or source of the compound. The Law of Multiple Proportions states that when two elements form more than one compound, the masses of the second element that combine with a fixed mass of the first are in ratios of small whole numbers. Finally, the Law of Energy Conservation deals with the principle that energy in a closed system is constant and can neither be created nor destroyed but can change from one form to another. Each of these principles plays a significant role