A radioactive isotope has a half-life of 15 hours15\text{ hours}15 hours. It emits radiation at a rate of 800 particles per second800\text{ particles per second}800 particles per second. How long does it take for the rate of emission to fall to 100 particles per second100\text{ particles per second}100 particles per second?
15 hours15\text{ hours}15 hours
30 hours30\text{ hours}30 hours
45 hours45\text{ hours}45 hours
60 hours60\text{ hours}60 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.