An isotope of iodine decays by β−\beta^-β− emission. It takes 32 days for its activity to fall to 116\displaystyle \frac{1}{16}161 of its original value. What is the half-life of the isotope?
2 days2\text{ days}2 days
8 days8\text{ days}8 days
16 days16\text{ days}16 days
128 days128\text{ days}128 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.