Answer: 1/8.
- A 1/8
- B 1/6
- C 1/3
- D 1/16
Correct answer: A. 1/8
Explanation: Each half-life halves the amount: after three half-lives the fraction left is (1/2)<sup>3</sup> = 1/8.
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.