In a medical laboratory, two freshly prepared samples of radiopharmaceuticals containing isotopes P P\,P and Q Q\,Q begin to decay at the same time. Isotope P P\,P has a half-life of 4.0 hours4.0\text{ hours}4.0 hours, and isotope Q Q\,Q has a half-life of 12.0 hours12.0\text{ hours}12.0 hours. After 24.0 hours24.0\text{ hours}24.0 hours, the number of remaining radioactive nuclei in both samples is measured to be identical. If the sample of isotope Q Q\,Q initially contained N N\,N radioactive nuclei, what was the initial number of radioactive nuclei in the sample of isotope PPP?
4N4N4N
8N8N8N
16N16N16N
64N64N64N
128 exam-style questions on AQA A Level Physics Radioactivity (A-level only), covering Rutherford scattering (A-level only), $\alpha$ , $\beta$ and $\gamma$ radiation (A-level only), Radioactive decay (A-level only), Nuclear instability (A-level only), Nuclear radius (A-level only), Mass and energy (A-level only), Induced fission (A-level only), and Safety aspects (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.