Final answer:
The Law of Conservation of Mass states that in a chemical reaction, the mass of the reactants equals the mass of the products, since mass is conserved and not created or destroyed. An example is burning charcoal, where the reactants' and products' masses are equal.
Step-by-step explanation:
The Law of Conservation of Mass states that A. The entire mass of a chemical reaction's products equals the entire mass of its reactants collectively. This principle is fundamental in chemistry and implies that during a chemical reaction, matter is neither created nor destroyed, but rather, it is conserved. In practical terms, this means that the total atomic mass of the reactants must be the same as the total atomic mass of the products, regardless of the changes that substances undergo during the reaction.
An example demonstrating this law is the reaction of charcoal burning in oxygen, where the mass of the charcoal and oxygen reacting must equal the mass of the carbon dioxide, water vapor, and ash produced. Despite the reactants and products being different substances, the total mass remains unchanged before and after the reaction.