The table shows the count rates obtained from four radioactive sources. The measurements were taken at noon on four consecutive days.
| Source | Day 1 | Day 2 | Day 3 | Day 4 |
|---|---|---|---|---|
| A | 800 | 600 | 440 | 320 |
| B | 1600 | 804 | 401 | 198 |
| C | 120 | 118 | 115 | 112 |
| D | 500 | 125 | 31 | 8 |
Which source has the shortest half-life?
Source A
Source B
Source C
Source D
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.