A. What is the half-life of 20 g of a radioactive sample if 5 g remain after 8 minutes? (1 point) B. Assume you have a 500 g sample of a radioactive isotope with a half-life of 100 years. Fill in the table showing how many grams of material will remain after the indicated time has passed. (2 points) Amount of Number of half-lives Years passed radioactive material remaining 0 0 500 g 2 3 C. How is the half-life of a radioactive material useful for radioactive dating? (1 point)