9. Answer the following questions on Half-Lives

a) What is a radioactive isotope _____________________________________________________________

b) What is radioactive decay? ______________________________________________________________

c) What is half-life? ______________________________________________________________

d) If we start with 400 atoms of a radioactive substance, how many would remain after one half-life?_________

after two half-lives? _________ after three half-lives? _________ after four half-lives? ________

e) If we start with 16 grams of a radioactive substance, how much will remain after three half-lives?________

f) If we start with 120 atoms of a radioactive substance, how many will remain after three half-lives?________

Use the following graph to answer questions A-D

a) How long is a half-life for C-14?___________

b) If only 25% of the carbon-14 remains, how old is the material containing the carbon-14? ________

c) If a sample originally had 120 atoms of C-14, how many atoms will remain after 16,110 years? _______

d) If a sample known to be about 10,740 years old has 400 carbon-14 atoms, how many atoms were in the sample when the organism died? _________

10. Which type of nuclear radiation (beta particles, gamma rays, or alpha particles) can be blocked by

a) a piece of paper ____________ b) a sheet of aluminum ____________ c) a piece of lead ____________