Which law states that mass is neither created nor destroyed in a chemical reaction?

• A. Law of Conservation of Energy
• B. Law of Conservation of Mass
• C. Law of Definite Proportions
• D. Law of Multiple Proportions

Answer: (B)

The Law of Conservation of Mass states that mass is neither created nor destroyed in a chemical reaction. This principle asserts that the total mass of reactants before a chemical reaction is equal to the total mass of the products after the reaction has occurred. This fundamental concept ensures that in any chemical process, the quantity of matter remains constant, even though it may change forms or be rearranged.

This law is crucial in understanding chemical equations, where the number and type of atoms must balance on both sides of the reaction. It underlies various scientific concepts and practices, such as stoichiometry, where calculations of reactants and products are based on the conservation of mass.

The other concepts mentioned, such as the Law of Conservation of Energy, focus on energy changes rather than mass, while the Laws of Definite and Multiple Proportions pertain to the proportions of elements in compounds rather than the conservation of mass during reactions.