A sample contains 8000 undecayed nuclei of an isotope. The half-life of the isotope is 6 hours. What does this half-life tell you?
After 6 hours the sample will have released half of its energy
After 6 hours the sample will have half of its original mass
After 6 hours about 4000 of the nuclei will not have decayed
After 12 hours none of the original 8000 nuclei will be left
40 exam-style questions on AQA GCSE Physics 4.2 Atoms and nuclear radiation, covering 4.2.1 Radioactive decay and nuclear radiation, 4.2.2 Nuclear equations, 4.2.3 Half-lives and the random nature of radioactive decay, and 4.2.4 Radioactive contamination. Each one has a worked solution and a mark scheme showing where the marks go.