Unit 1: Lesson 3: Dating With Radioactivity Assessment Questions Study Guide Questions And Correct Answers

Which of the following could not be dated using radiocarbon dating: charcoal, wooden beam, clay pot, food in the clay pot? Explain. {Ans: the clay pot, because clay is not an organic material}How do geologists use radiometric dating to date sedimentary rock layers indirectly? {Ans: Sedimentary rock layers that lie between two igneous rock units must have an age that lies somewhere between the absolute ages of the two igneous rock units. The latter can be dated using radiometric methods.}What is the role of isotopes in radiometric dating? {Ans: A radioactive isotope decays into its stable daughter product at a constant rate. The time it takes for half of the isotope in a sample to decay is known as the half-life of the isotope. A radioactive isotope can thus serve as a "clock" that can be used to determine the age of a substance.}A geologist wants to use potassium-argon dating to date a granite rock found on the surface. What is a possible source of inaccuracy in dating the rock? {Ans: The rock may have been contaminated by other sources of potassium-40 on the surface. For radiometric dating to be accurate, a sample must remain in