Question Detail
Question
A powder contains 400 mg of a radioactive material that emits α-particles. The half-life of the material is 5 days. What mass of that material remains after 10 days?
Correct Answer
Option C is the correct answer.
Detailed Explanation
10 days is 2 half-lives (since half-life is 5 days). After 1 half-life (5 days), 200 mg remains. After 2 half-lives (10 days), 100 mg remains.
Hint
The mass halves every half-life.