568 Nuclear StructureQ44.104He, 16O, 40Ca, and 208Pb.Q44.11If one half the number of radioactive nuclei decay in one year, then one half the remaining numberwill decay in the second year. Three quarters of the original nuclei will be gone, and one quarter willremain.Q44.12The statement is false. Both patterns show monotonic decrease over time, but with very differentshapes. For radioactive decay, maximum activity occurs at time zero. Cohorts of people now livingwill be dying most rapidly perhaps forty years from now. Everyone now living will be dead withinless than two centuries, while the mathematical model of radioactive decay tails off exponentiallyforever. A radioactive nucleus never gets old. It has constant probability of decay however long ithas existed.Q44.13Since the samples are of the same radioactive isotope, their half-lives are the same. When prepared,sample A has twice the activity (number of radioactive decays per second) of sample B. After 5 half-
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