Radioactive decay and half-life Quiz
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5 questions, one answer each
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1. A sample has an activity of 800 Bq and a half-life of 20 min. What is its activity after 60 min?
- A. 400 Bq
- B. 200 Bq
- C. 100 Bq
- D. 50 Bq
2. What is the half-life of an isotope with a decay constant of 0.0050 s⁻¹?
- A. 139 s
- B. 200 s
- C. 3.5 s
- D. 0.0035 s
3. A graph of ln A against t has a gradient of −0.025 h⁻¹. What is λ?
- A. −0.025 h⁻¹
- B. 0.025 h⁻¹
- C. 40 h⁻¹
- D. 0.69 h⁻¹
4. Which of these quantities is equal to λN?
- A. The number of undecayed nuclei
- B. The half-life
- C. The activity
- D. The decay probability of the whole sample
5. A sample has N = 5.0 × 10¹⁰ nuclei and λ = 4.0 × 10⁻⁶ s⁻¹. What is its activity?
- A. 2.0 × 10⁵ Bq
- B. 1.3 × 10¹⁶ Bq
- C. 2.0 × 10⁴ Bq
- D. 8.0 × 10⁻⁵ Bq