1. While working at an ancient burial ground, scientists unearth a tree branch that has level of C-14 that is approximately 1/32 of the current atmospheric 14C levels. Calculate your answers to the following and be sure to show your work. In answering this question, you may find it helpful to reference the C-14 data table you completed with the lab activity.
· Approximately how long ago was the tree branch broken off from the rest of the tree?
· If there were 1,500,000 carbon-14 atoms in the tree branch to begin with, how many atoms would remain?
2. Consider that Carbon-14 has a half-life of 5,750 years and the following timeline. Why is carbon-14 used to evaluate the age of ancient human remains, but is not used to date dinosaur bones?
3. The half-life of a sample of potassium-40 (40K) is approximately 1.3 billion years. Potassium-40 decays into argon-40 (40Ar). Some rocks containing potassium-40 have been here since the earth formed and have been accumulating argon-40 to the present day. When rocks are super-heated by volcanic action, all the 40Ar escapes the rock. Discuss how geologists use potassium-argon dating to determine how long ago a volcanic eruption occurred, making sure to base your answer on your understanding of half-life.