Question

Carbon-14 has a half-life of 5,730 years. If the age of an object older than 50,000 years cannot be determined by radiocarbon dating, then

A. carbon-14 levels in a sample are undetectable after approximately fourteen half-lives.

B. carbon-14 levels in a sample are undetectable after approximately nine half-lives.

C. the half-life of carbon-14 is too long to accurately date the object.

D. a radioisotope with a shorter half-life should be used to date the object.

Answer 1

how many half-lives are 50000 years, when 1 half-life is 5730 years?

Answer 2

\(\dfrac{50000~years}{5730~years/t_{1/2}}=8.7260 ~t_{1/2}\)

so 50,000 is approximately 9 half-lives.