Multiple Choice
Identify the
letter of the choice that best completes the statement or answers the question.

 1.  According to the graph below, what is the halflife of the radioactive nuclide
strontium90?
a.  10
years  c.  50
years  b.  25 years  d.  100 years     

 2.  The
halflife of element X is 10.0 days. If you start with a 128 gram sample of element X, what
mass of element X remains after a period of 50.0 days? a.  4.00
g  c.  2.56
g  b.  12.8
g  d.  25.6
g     

 3.  The
halflife of carbon14 is 5730 years. What fraction of a carbon14 sample would exist after
22920 years?

 4.  A
sample of the radioactive isotope radon222 has an initial mass of 10.0 grams. After 15 days,
approximately 0.63 grams of radon222 remains. What is the halflife of
radon222? a.  10
days  c.  3.8
days  b.  5
days  d.  7.5
days     

 5.  A
piece of wood found in an ancient burial mound contains only half as much carbon14 as a piece of
wood cut from a living tree growing nearby. If the halflife (T_{1/2})for carbon is
5730 years, what is the approximate age of the ancient wood? a.  1432.5
years  c.  5730
years  b.  2856 years  d.  1460 years     

 6.  The
decay rate of an ancient wood carving is onefourth that of the decay rate of carbon14 in living
tissue. (The halflife of carbon14 is 5730 years.) How old is the
carving? a.  1432
years  c.  11460
years  b.  5730 years  d.  17190 years     
