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 a) determine k for the first order radioactive decay b) calculate the fraction of sr-90 that remains after 10 half-lives. c) calculate the time required for 99.3% of sr-90 to disappear. d) sr-90 is linked to bone cancer in persons who have lived near a nuclear event. why? e) a sample of bone tissue was unearthed at a crime scene was analyzed for sr-90. it was found that the bone sample contained 21.67% 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 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