What is the difference between a reactant and a product?

In a chemical reaction, the fundamental distinction between reactants and products lies in their roles during the reaction process. Reactants are the substances that undergo change and are consumed in the reaction, meaning they are present at the beginning and are transformed or used up to create new substances. On the other hand, products are the substances that are formed as a result of the chemical reaction; they appear after the reactants have been converted.

Understanding this distinction is crucial in predicting the outcome of reactions, balancing chemical equations, and identifying the materials involved in various processes. This definition aligns with the basic principles of chemistry that govern reactant-product relationships, emphasizing the transformation that occurs during chemical reactions.

The other options do not accurately describe the roles of reactants and products. For example, the claim that reactants form as a result of the reaction is misleading, and the statements regarding the states of matter for reactants and products are overly restrictive and not universally applicable.