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
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.