Nuclear Decay and Radioactivity (4E) Practice Test

A radiopharmacy prepares $^{125}\text{I}$ seeds for brachytherapy; $^{125}\text{I}$ decays by electron capture to $^{125}\text{Te}$. The half-life is 59 days. Two identical sealed seeds are stored: Seed 1 is stored for 59 days; Seed 2 is stored for 118 days. What prediction can be made about the decay rate (activity) of Seed 2 relative to Seed 1 at the time of use, assuming identical initial activity?

A researcher labels red blood cells with $^{51}\text{Cr}$ to track cell survival. $^{51}\text{Cr}$ decays primarily by electron capture to $^{51}\text{V}$ with a half-life of 27.7 days (decay constant $\lambda \approx 2.9\times 10^{-7}\ \text{s}^{-1}$). Which statement best describes the decay process illustrated?