Mathematics

1. (10 pts) With the help of the periodic table, give the number of protons, neutrons, and electrons in the following isotopes:    (a)  strontium-90   (b)  cesium-137   (c)  iodine-131.       These radioisotopes are present in nuclear fallout from bomb tests in the atmosphere, and their chemistry is such that they can easily be taken up in the human body.  Their bad effects on the human body are influenced by their half lives.  What is the half life of each of these isotopes, respectively?  (a)                            (b)                  (c)           2. (5 pts) In an experiment, 1.6 grams of Sr-90 was buried in 1952.  How much of this sample is still Sr-90 in 2008?