What does the law of conservation of mass state?

The law of conservation of mass states that, in a closed system, mass is neither created nor destroyed during a chemical reaction. Instead, the total mass of the reactants is equal to the total mass of the products. This means that while the substances involved in the reaction may change forms—such as solid to liquid or gas to solid—the total amount of matter remains constant throughout the reaction process.

Choosing the option that states mass can only change forms reflects an understanding of this principle. It emphasizes that the mass involved in the reaction is conserved, and while it may undergo transformations—like an element combining with another to form a compound or a substance undergoing phase changes—the overall mass tally does not fluctuate.

The other options suggest ideas contrary to the law. Creation or destruction of mass during a reaction would violate this fundamental principle, and converting mass directly into energy pertains to Einstein's theory of relativity rather than the chemical conservation of mass. Therefore, the correct interpretation aligns with the understanding that mass changes forms rather than being created or destroyed in chemical transformations.