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Checking Background in a Decay Simulation 4 questions
Checking Background in a Decay Simulation
Base your answers on the information provided and your knowledge of chemistry. Use the 2025 Chemistry Reference Tables as needed.
A classroom simulation represents a detector counting emissions from a decaying sample. The detector also records background events. The background stays constant over the run. Every reading is taken over the same one-minute counting interval, and the counting intervals are short compared with the sample’s half-life.
| Elapsed time (h) | Counts in one minute |
|---|---|
| 0 | 100 |
| 4 | 60 |
| 8 | 40 |
| 12 | 30 |
A student says the half-life must be greater than four hours because the total count after four hours is still above half its original value. A separate run with no sample gives 20 counts in one minute.
Question 1
Calculate the sample-only counts at zero hours and four hours. Use the no-sample reading.
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Question 2
Which half-life best fits the corrected counts?
- 2 h
- 4 h
- 8 h
- 12 h
Question 3
Explain why the total count does not halve after one half-life in this simulation.
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Question 4
Predict the total count at 16 hours if the same model continues. Show how you included both sources of counts.
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