Answer: Large excess.
- A Large excess
- B Very low concentration
- C Gas phase
- D Solid phase
Correct answer: A. Large excess
Explanation: When one reactant is in huge excess, its concentration barely changes, making the reaction appear first-order.
First-order decay curve: concentration halves every t½, and that half-life is constant - a defining test for first-order kinetics.
Concept context
Study the speed of reactions and what affects it: concentration, temperature, and catalysts. Covers rate law, order of reaction, the Arrhenius equation, and reaction mechanisms step by step.