During stoichiometric calculations, which of the following laws must be followed?

Explanation

Option A describes the law of partial pressures, which states that the total pressure by a mix of gases is equal to the sum of partial pressures of each of the constituent gases.Option B describes the law which states that equal volumes of gases, at the same temperature and pressure, contain equal numbers of molecules. (NOTE: Do not confuse this with Avogadro's number and the concept of a mole).Option C describes the law which states that matter can neither be created nor destroyed so, the mass of every element, present in the products of a chemical reaction, must be equal to the mass of each and every element present in the reaction, on the reactant side. This is the basis of balancing a chemical equation, without which stoichiometric calculations cannot be carried out so, it is the correct answer.Option D describes the law which states that energy can neither be created nor destroyed; it can only be transferred from one form to the other. This has more relevance in energy conversion and work or power calculations rather than stoichiometry.