Final answer:
The correct answer is that the mass of reactants equals the mass of products as per the law of conservation of mass. This principle indicates mass is conserved in a closed system during chemical reactions, shown in the synthesis of water from hydrogen and oxygen.
Step-by-step explanation:
The correct representation of the law of conservation of mass as it applies to chemical reactions is that the mass of reactants equals the mass of products. This fundamental principle establishes that during any given chemical reaction in a closed system, the total mass will remain unchanged, meaning mass is neither created nor destroyed. To illustrate, consider a simple chemical reaction such as the combination of hydrogen gas (H2) with oxygen gas (O2) to form water (H2O). If you start with 2 grams of hydrogen and 16 grams of oxygen, you will end up with 18 grams of water, demonstrating that the mass before and after the reaction is the same.