37. Determine the 14C activity in disintegrations per second (dps) of a wooden artifact that is 23,000 years old. (Assume that fresh-cut wood of equal mass has an activity of 15.2 dps.) The half-life of 14C is 5715 years. 38. Iron-59 decays to cobalt via beta emission with a half-life of 45.1 days. From the diagram, determine how many half-lives have elapsed since the sample was pure iron-59. Co Co Co Co Fe Co Co Co Co Co Co Fe Co Co Co Co Cobalt Iron-59 Co Fe 39. The radioactive decay of TI-206 to Pb-206 has a half-life of 4.20 min. Starting with 5.00 1022 atoms of TI-206, calculate the number of such atoms left after 42.0 min. 40. A wooden artifact has a 14C activity of 18.9 disintegrations per minute, compared to 27.5 disintegrations per minute for live wood. Given that the half-life of 14C is 5715 years, determine the age of the artifact. 87