Answer: 8×103 Bq.
- A 3.2×104 Bq
- B 1.6×104 Bq
- C 8×103 Bq
- D 2×104 Bq
Correct answer: C. 8×103 Bq
Explanation: 9 hours = 3 half-lives, so activity = 6.4 × 104/23 = 6.4 × 104/8 = 8 × 103 Bq.
Binding energy per nucleon rises sharply for light nuclei, peaks around iron-56 (the most stable nucleus), then slowly declines for heavier nuclei - which is exactly why fusing light nuclei or splitting heavy nuclei both release energy: each moves the products toward this stability peak.
Concept context
Radioactivity, nuclear reactions, fission, fusion, and binding energy.