In an experiment to determine the half-life of a particular radionuclide, measurements of the mass of that nuclide are made. If masses of 8 micrograms and 2 micrograms are recorded at intervals 8 days apart, what is the half-life of the nuclide?

C: If we start with 8 μg of a radionuclide and when it decays it becomes another nuclide, then after one half-life there will be 4 μg remaining and after another half-life, there will be 2 μg. Hence two half-lives have elapsed during the 8 day period. This means one half life is 8 ÷ 2 = 4 days.