One of the problems of in-air testing of nuclear weapons (or, even worse, theuseof such weapons!) is the danger of radioactive fallout. One of the most problematic nuclides in such fallout is strontium -90(90 Sir), which breaks down byB -decay with a half-life of 28 years. It is chemically similar to calcium and therefore can be incorporated into bones and teeth, where, due to its rather long half-life, it remains for years as an internal source of radiation.
a) what is the daughter nucleus
b) What percent of the original is left after 56 years?
c) How long would you have to wait for the original level to be reduced to 0.195% of its original value?