The following questions are designed to give you practice using tables and learn more about the chemical and physical characteristics of plutonium. These questions are based on the table entitled Important Radiological Properties of Plutonium Isotopes .

1. What are the units used in the table for the half-life of the isotopes?

Answer: Years

2. (a) What is the half-life of Pu-242? (b) in scientific notation?

Answer: 376,000 years or 3.76 x 10⁵ years in scientific notation

3. Which of the plutonium isotopes presented in the centerfold table has the longest half-life?

Answer: Pu-242

4. What is the specific activity of Pu-238 in curies/gram?

Answer: 17.3 Ci/gram (Ci is the symbol for curies)

5. (a) What is the specific activity of Pu-238 in curies/kilogram? (b) in scientific notation?

Answer: (a) (17.3 Ci/g) x (1000 g/kg) = 17,300 Ci/kg
(b) 1.73 x 10⁴ Ci/kg

6. (a) How many curies are there in one tonne of pure Pu-238? (b) in scientific notation?

Answer: (a) (17,300 Ci/kg) x (1,000 kg/tonne) = 17,300,000 Ci/tonne
(b) 1.73 x 10⁷ Ci/tonne

7. (a) How many curies are there in one tonne of pure Pu-239? (b) in scientific notation?

Answer: (a) (0.063 Ci/g)x(1,000 g/kg)x(1,000 kg/tonne)x(1 tonne)=63,000 Ci
(b) 6.3 x 10⁴ Ci

8. Which isotope of plutonium is more radioactive per unit mass (gram), Pu-238 or Pu-239?

Answer: Pu-238

9. What is the specific activity of Pu-242 in bequerels/gram?

Answer: (0.004 Ci/g) x (37 x 10⁹ Becquerel/Ci) = 1.48 x 10⁸ Bq/g (Bq is the symbol for becquerel)

Institute for Energy and Environmental Research

Comments to Outreach Coordinator, Pat Ortmeyer: ieer@ieer.org
Takoma Park, Maryland, USA

Last Updated April 17, 1996