A sample contains 0.0036 g of a radioactive isotope. After 9.0 hours9.0\text{ hours}9.0 hours the mass of the radioactive isotope in the sample falls to 0.00090 g. What is the half-life of the radioactive isotope?
3.0 hours3.0\text{ hours}3.0 hours
4.5 hours4.5\text{ hours}4.5 hours
9.0 hours9.0\text{ hours}9.0 hours
18 hours18\text{ hours}18 hours
484 exam-style questions on CIE IGCSE Physics 5.2 Radioactivity, covering 5.2.1 Background radiation and measuring count rate, 5.2.2a Alpha, beta and gamma emission, 5.2.2b Deflection and ionising effects of nuclear radiation, 5.2.3a Radioactive decay, 5.2.3b Effects of decay on the nucleus and decay equations, 5.2.4a Half-life, 5.2.4b Choosing isotopes for applications, and 5.2.5 Effects of ionising radiation and safety precautions. Each one has a worked solution and a mark scheme showing where the marks go.