The table shows the results of an experiment to find the half-life of a radioactive substance.
| Time / minutes | Count rate / (counts / minute) |
|---|---|
| 0 | 400 |
| 10 | 317 |
| 20 | 252 |
| 30 | 200 |
| 40 | 159 |
| 50 | 126 |
What is the half-life of the substance?
10 minutes10\text{ minutes}10 minutes
20 minutes20\text{ minutes}20 minutes
30 minutes30\text{ minutes}30 minutes
40 minutes40\text{ minutes}40 minutes
144 exam-style questions on CIE IGCSE Physics 5.2.4a Half-life. Each one has a worked solution and a mark scheme showing where the marks go.