Dating Problems: Use the table below to answer the following questions.
1. A certain rock sample was found to contain equal amounts of Uranium-235 and Lead-207. How old is
the rock sample?
2. Pieces of clothing were found in a nearby cave and analyzed for age. The clothing was found to have
¾ Nitrogen-14. Estimate their age.
3. A fossilized shell was analyzed for Potassium-40 and Argon-40 ratios and determined to be 2.5 billion
years old. How many half-lives is this?
4. A fossil was found to have 1:31 atoms of Potassium-40. Estimate its age.
5. If dinosaurs walked the Earth about 2 million years ago, would it be possible to date a dinosaur fossil?
Isotopes used for Radioactive Dating
Isotope Pair
Half-Life (yrs) Useful Range (yrs)
Carbon-14 to Nitrogen-14
5730
60, 000 ago
Uranium-235 to Lead-207
700, 000,000
Over 500,000
Potassium-40 to Argon-40 1,250,000,000
Over 500,000
Uranium-238 to Lead-206 4,500,000,000
Over 100,000,000
Dating Problems: Use the table below to answer the following questions.
1. A certain rock sample was found to contain equal amounts of Uranium-235 and Lead-207. How old is
the rock sample?
2. Pieces of clothing were found in a nearby cave and analyzed for age. The clothing was found to have ¾
Nitrogen-14. Estimate their age.
3. A fossilized shell was analyzed for Potassium-40 and Argon-40 ratios and determined to be 2.5 billion
years old. How many half-lives is this?
4. A fossil was found to have 1:31 atoms of Potassium-40. Estimate its age.
5. If dinosaurs walked the Earth about 2 million years ago, would it be possible to date a dinosaur fossil?
Isotopes used for Radioactive Dating
Isotope Pair
Half-Life (yrs)
Carbon-14 to Nitrogen-14 5730
Uranium-235 to Lead-207 700, 000,000
Potassium-40 to Argon-40 1,250,000,000
Uranium-238 to Lead-206 4,500,000,000
Useful Range (yrs)
60, 000 ago
Over 500,000
Over 500,000
Over 100,000,000
Dating Problems: Use the table below to answer the following questions.
1. A certain rock sample was found to contain equal amounts of Uranium-235 and Lead-207. How old is
the rock sample?
2. Pieces of clothing were found in a nearby cave and analyzed for age. The clothing was found to have ¾
Nitrogen-14. Estimate their age.
3. A fossilized shell was analyzed for Potassium-40 and Argon-40 ratios and determined to be 2.5 billion
years old. How many half-lives is this?
4. A fossil was found to have 1:31 atoms of Potassium-40. Estimate its age.
5. If dinosaurs walked the Earth about 2 million years ago, would it be possible to date a dinosaur fossil?
Isotopes used for Radioactive Dating
Isotope Pair
Half-Life (yrs)
Carbon-14 to Nitrogen-14 5730
Uranium-235 to Lead-207 700, 000,000
Potassium-40 to Argon-40 1,250,000,000
Uranium-238 to Lead-206 4,500,000,000
Useful Range (yrs)
60, 000 ago
Over 500,000
Over 500,000
Over 100,000,000
Dating Problems: Use the table below to answer the following questions.
1. A certain rock sample was found to contain equal amounts of Uranium-235 and Lead-207. How old is
the rock sample?
2. Pieces of clothing were found in a nearby cave and analyzed for age. The clothing was found to have ¾
Nitrogen-14. Estimate their age.
3. A fossilized shell was analyzed for Potassium-40 and Argon-40 ratios and determined to be 2.5 billion
years old. How many half-lives is this?
4. A fossil was found to have 1:31 atoms of Potassium-40. Estimate its age. 6.25 billion
5. If dinosaurs walked the Earth about 2 million years ago, would it be possible to date a dinosaur fossil
using carbon 14?
Isotopes used for Radioactive Dating
Isotope Pair
Half-Life (yrs)
Carbon-14 to Nitrogen-14 5730
Uranium-235 to Lead-207 700, 000,000
Potassium-40 to Argon-40 1,250,000,000
Uranium-238 to Lead-206 4,500,000,000
Useful Range (yrs)
60, 000 ago
Over 500,000
Over 500,000
Over 100,000,000