A sample of a radioactive isotope has an initial rate of emission of 240 counts per minute240\text{ counts per minute}240 counts per minute and a half-life of 6 days6\text{ days}6 days.
How long will it take for the rate of emission to fall to 30 counts per minute30\text{ counts per minute}30 counts per minute?
6 days6\text{ days}6 days
12 days12\text{ days}12 days
18 days18\text{ days}18 days
24 days24\text{ days}24 days
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.