Question

1. Sr-90 is a radioactive isotope that is a major product of an atomic bomb explosion. It is not found naturally in nature. It has a half-life of 28.1 years.
   1. Determine k for the first order radioactive decay.
   2. Calculate the fraction of Sr-90 that remains after 10 half-lives.
   3. Calculate the time required for 89.3% of Sr-90 to disappear.
   4. Sr-90 is linked to bone cancer in persons who have lived near a nuclear event. Why?
   5. A sample of bone tissue was unearthed at a crime scene was analyzed for Sr-90. It was found that the bone sample contained 1.27% of a similar sample of bone from a person alive today in the area where the fragment was found. Estimate the point in time when the person died.
   6. Another bone fragment was analyzed for Sr-90. There was no Sr-90 found in the bone. Assuming that the analytical method used to analyze for Sr-90 is accurate to the atomic level (yes, such a method exists), what can be said about the minimum age of the bone fragment.

Answer 1