Which statement about radiocarbon dating using C-14 is true?

Which statement about radiocarbon dating using C-14 is true?

• A. It uses C-14 to estimate ages of organic materials up to about 50,000 years
• B. It uses uranium-235
• C. It uses lead-lead dating
• D. It uses potassium-40 dating

Answer: (A)

Radiocarbon dating relies on the decay of carbon-14, a radioactive isotope formed in the atmosphere and incorporated into living matter. When an organism is alive, it maintains a constant level of C-14 by exchanging carbon with its surroundings. After death, intake stops and C-14 decays to nitrogen-14 with a half-life of about 5,730 years. By measuring how much C-14 remains in a sample and comparing it to the initial atmospheric level, we can estimate the time since death. This method is effective for organic materials up to roughly 50,000 years old because beyond that the remaining C-14 becomes extremely small and difficult to measure accurately. Calibration is often used to account for past variations in atmospheric C-14 levels and improve accuracy. The other dating methods listed—uranium-235 dating, lead-lead dating, and potassium-40 dating—are suited to very different materials and timescales (mostly rocks and minerals, often millions of years old), not to organic carbon and the tens of thousands-of-years range.

Radiocarbon dating relies on the decay of carbon-14, a radioactive isotope formed in the atmosphere and incorporated into living matter. When an organism is alive, it maintains a constant level of C-14 by exchanging carbon with its surroundings. After death, intake stops and C-14 decays to nitrogen-14 with a half-life of about 5,730 years. By measuring how much C-14 remains in a sample and comparing it to the initial atmospheric level, we can estimate the time since death.

This method is effective for organic materials up to roughly 50,000 years old because beyond that the remaining C-14 becomes extremely small and difficult to measure accurately. Calibration is often used to account for past variations in atmospheric C-14 levels and improve accuracy.

The other dating methods listed—uranium-235 dating, lead-lead dating, and potassium-40 dating—are suited to very different materials and timescales (mostly rocks and minerals, often millions of years old), not to organic carbon and the tens of thousands-of-years range.