The table below shows the results of an experiment to find the half-life of a radioactive substance.
| Time (minutes) | Count rate from substance (counts / minute) |
|---|---|
| 0 | 240 |
| 40 | 190 |
| 80 | 150 |
| 120 | 120 |
| 160 | 95 |
What is the half-life of the substance?
40 minutes
80 minutes
120 minutes
160 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.