The count rate due to a sample of a radioactive isotope is measured for 120 minutes.
| Time / minutes | Count rate / counts/second |
|---|---|
| 0 | 800 |
| 30 | 635 |
| 60 | 504 |
| 90 | 400 |
| 120 | 317 |
What is the half-life of the isotope?
30 minutes30\text{ minutes}30 minutes
60 minutes60\text{ minutes}60 minutes
90 minutes90\text{ minutes}90 minutes
120 minutes120\text{ minutes}120 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.