Final answer:
According to Le Châtelier's Principle, applying heat to an exothermic reaction shifts the equilibrium towards the reactants, and for an endothermic reaction, towards the products. The correct option is B. Reactants; Products.
Step-by-step explanation:
According to Le Châtelier's Principle, heat applied to an exothermic reaction will shift the reaction towards the reactants. Heat applied to an endothermic reaction will shift the reaction towards the products. Therefore, the correct option is B. Reactants; Products.
In exothermic reactions, heat can be considered a product of the reaction. When heat is added, the system will try to counteract this change by shifting the equilibrium towards the reactants to absorb this extra heat. Conversely, in endothermic reactions, heat is treated as a reactant. Adding heat shifts the equilibrium towards the products as the system attempts to consume the added heat.
Decreasing temperature has the opposite effect. Cooling an exothermic reaction will cause the reaction to shift toward the product side; cooling an endothermic reaction would cause it to shift to the reactants' side.