Which of the following best describes a method to balance chemical equations?

The best method to balance chemical equations is to apply the principles of conservation of mass. This principle states that in a chemical reaction, the mass of the reactants must equal the mass of the products. Consequently, this means that the number of each type of atom must be the same on both sides of the equation.

To balance a chemical equation, one typically uses coefficients to ensure that the number of atoms for each element is equal in both the reactants and products. This method effectively reflects the conservation of mass, as it ensures that the same quantities of substances that enter a reaction (reactants) are accounted for in the substances that result from the reaction (products).

The other methods suggested do not accurately reflect the proper way to balance a chemical equation. For instance, adding coefficients to all reactants without considering the products may lead to an imbalance. Simply counting the number of atoms after the reaction disregards the necessity of balancing the equation from the outset since atomic count must be equal pre- and post-reaction. Lastly, using energy levels to balance does not pertain to the stoichiometric balance of chemical equations and instead relates to atomic structure and bonding. Therefore, understanding and applying the conservation of mass is essential in correctly balancing chemical equations.