The half-life of a radioactive nuclide is 3.0 hours3.0\text{ hours}3.0 hours.
The decay rate of a sample of this nuclide is measured at 1.5 hour1.5\text{ hour}1.5 hour intervals. The table shows the measurements, with one value shown as XXX.
| Time (hours) | Decay rate (decays / s) |
|---|---|
| 0 | 320 |
| 1.5 | 226 |
| 3.0 | 160 |
| 4.5 | 113 |
| 6.0 | XXX |
What is the most likely value of XXX?
404040
565656
808080
113113113
484 exam-style questions on CIE IGCSE Physics 5.2 Radioactivity, covering 5.2.1 Background radiation and measuring count rate, 5.2.2a Alpha, beta and gamma emission, 5.2.2b Deflection and ionising effects of nuclear radiation, 5.2.3a Radioactive decay, 5.2.3b Effects of decay on the nucleus and decay equations, 5.2.4a Half-life, 5.2.4b Choosing isotopes for applications, and 5.2.5 Effects of ionising radiation and safety precautions. Each one has a worked solution and a mark scheme showing where the marks go.