Question

which isotope is appropriate for dating rocks that are billions of years old?
carbon-12
uranium-238
oxygen-16
carbon-14

Explanation:

• Carbon - 12 and oxygen - 16 are stable isotopes and do not undergo radioactive decay, so they cannot be used for radiometric dating.
• Carbon - 14 has a relatively short half - life (\(t_{1/2}=5730\) years) and is suitable for dating materials up to about 50,000 - 60,000 years old.
• Uranium - 238 has a very long half - life (\(t_{1/2}=4.5\times10^{9}\) years), which makes it appropriate for dating rocks that are billions of years old.

Answer:

Uranium - 238