Which statement best describes a reversible reaction?

Which statement best describes a reversible reaction?

• A. A reaction that proceeds in one direction only.
• B. A reaction that occurs spontaneously.
• C. A reaction in which products can reform reactants.
• D. A reaction that is catalyzed by an enzyme.

Answer: (C)

Reversible reactions are those where the same chemical change can go in both directions. In a closed system at a given temperature, both the forward reaction (reactants to products) and the reverse reaction (products back to reactants) occur, and their rates can balance out so the amounts of each species stay constant at equilibrium. This interconvertibility is what allows products to reform the original reactants when conditions favor the reverse direction. The other statements don’t capture reversibility: something that proceeds in one direction only is irreversible; spontaneity concerns energy changes and not whether the reaction can run in reverse; and a reaction catalyzed by an enzyme speeds up the process but doesn’t define reversibility, since enzymes can influence both directions depending on thermodynamics.

Reversible reactions are those where the same chemical change can go in both directions. In a closed system at a given temperature, both the forward reaction (reactants to products) and the reverse reaction (products back to reactants) occur, and their rates can balance out so the amounts of each species stay constant at equilibrium. This interconvertibility is what allows products to reform the original reactants when conditions favor the reverse direction. The other statements don’t capture reversibility: something that proceeds in one direction only is irreversible; spontaneity concerns energy changes and not whether the reaction can run in reverse; and a reaction catalyzed by an enzyme speeds up the process but doesn’t define reversibility, since enzymes can influence both directions depending on thermodynamics.