Two radioactive isotopes commonly used in diagnostic imaging are technetium-99m (half-life 6.0 h) and iodine-123 (half-life 13 h). Equal numbers of nuclei of each isotope are simultaneously administered to a patient for two separate scans.
(a) Describe what is meant by the half-life of a radioactive isotope in the context of this situation.
(b) Based solely on their half-lives, identify which isotope is the more stable nucleus. Justify your answer.
(c) During the first 3 h after administration, which isotope undergoes the greater number of decays? Provide a qualitative explanation that ties your conclusion to each isotope’s half-life and decay rate.