What does the law of conservation of mass state?

The law of conservation of mass states that mass remains constant in all chemical reactions, meaning that the total mass of reactants equals the total mass of products. This principle is foundational in chemistry and implies that during a chemical reaction, while the molecules may rearrange to form new substances, the total amount of matter involved does not change. This ensures that atoms are neither created nor destroyed through the reaction process, solidifying the concept that mass is conserved.

In contrast to this principle, the other options suggest different outcomes regarding mass during reactions. Some incorrectly imply that mass can be created or destroyed, which contradicts the established understanding that mass is conserved throughout any physical or chemical change. The idea that mass can change form but not amount may seem plausible but does not accurately reflect the core principle that mass remains unchanged in total through any such process.