Naturally occurring cobalt has an atomic mass of 58.9332 amu. A sample of cobalt with a total mass of 8.56 g and an apparent atomic mass of 59.0509 amu was found to be contaminated with Co-60. Co-60 is a synthetic radioisotope of cobalt used as a radiation therapy of some cancer. The atomic mass of the isotope, Co-60, is 59.9338 amu.
Dear visitor! Please clarify your question. There is no task in its statement.