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CP LC Online Half-Life Practice Problems

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 half-life of the radioactive nuclide strontium-90?

 a. 10 years c. 50 years b. 25 years d. 100 years

2.

The half-life 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 half-life of carbon-14 is 5730 years.  What fraction of a carbon-14 sample would exist after 22920 years?
 a. 1/32 c. 1/4 b. 1/8 d. 1/16

4.

A sample of the radioactive isotope radon-222 has an initial mass of 10.0 grams.  After 15 days, approximately 0.63 grams of radon-222 remains.  What is the half-life of radon-222?
 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 carbon-14 as a piece of wood cut from a living tree growing nearby.  If the half-life (T1/2)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 one-fourth that of the decay rate of carbon-14 in living tissue.  (The half-life of carbon-14 is 5730 years.)  How old is the carving?
 a. 1432 years c. 11460 years b. 5730 years d. 17190 years