Which of the following best explains why carbon-14 is the most common isotope used for radiometric dating of once-living materials?

• A. Carbon-14 is present in all living organisms and has a half-life suitable for dating materials up to about 50,000 years old.
• B. Carbon-14 is the most abundant isotope of carbon in nature.
• C. Carbon-14 is stable and does not undergo radioactive decay.
• D. Carbon-14 decays into oxygen, which is easily detected.

Answer: (A)

Verified step by step guidance

1. Understand the concept of radiometric dating: it relies on measuring the decay of radioactive isotopes within once-living materials to estimate their age.
2. Recognize that the isotope used must be present in living organisms so that it can be incorporated into their tissues while alive.
3. Consider the half-life of the isotope: it should be long enough to measure ages of interest but not so long that decay is negligible over the timescale studied.
4. Evaluate the options: Carbon-14 is radioactive (not stable), decays into nitrogen (not oxygen), and is not the most abundant carbon isotope (that is Carbon-12).
5. Conclude that Carbon-14 is ideal because it is present in all living organisms and has a half-life (~5730 years) suitable for dating materials up to about 50,000 years old.