1- Find the decay constant of cesium-137, half-life 30.2 y; then calculate the activity in becquerels and curies for a sample containing 3 1019 atoms.
2- Calculate the activity A for 1 g of radium-226 with the modern value of the half-life, and compare it with the definition of a curie.
3- A capsule of cesium-137, half-life 30.2 y, is used to check the accuracy of detectors of radioactivity in air and water. Draw a graph on semilog paper of the activity over a 10 y period of time, assuming the initial strength is 1 mCi. Explain the results
4- There are approximately 140 grams of potassium in a typical person's body. From this weight, the abundance of potassium-40, and Avogadro's number, find the number of atoms. Find the decay constant in s1. How many disintegrations per second are there in the body? How many becquerels and how many microcuries is this?