Question

The isotope known as carbon-14 is radioactive and will decay into the stable form nitrogen-14. As long as an organism is alive, it ingests air, and the level of carbon-14 in the organism remains the same. When it dies, it no longer absorbs carbon-14 from the air, and the carbon-14 in the organism decays.

The half-life of carbon-14 is 5770 years. Assume an organic sample is 15,000 years old.

Determine how many half-lives are in 15,000 years. Then use this answer to determine what percentage of the original amount of carbon-14 remains after 15,000 years. Round your answer as a percentage to the nearest whole number.
_____%

Answer 1

The half life would be about 3 so making the percentage About 25%

Answer 2

9514 1404 393

Answer:

• about 2.6 half-lives
• 16% remains

Explanation:

The number of half-lives is ...

(15000 yr)/(5770 yr/half-life) = 2.6 half-lives

__

Then the amount of C14 remaining after 15000 years is ...

0.5^2.6 ≈ 0.1649 ≈ 16%