The radioactive decay of carbon-14 is first-order and the half-life is 5800 years. While a plant

Question

or animal is living, it has a constant proportion of carbon-14 (relative to carbon-12) in its
composition. When the organism dies, the proportion of carbon-14 decreases as a result of
radioactive decay and the age of the organism can be determined if the proportion of carbon14
in its remains is measured. If the proportion of carbon-14 in an ancient piece of wood is
found to be one quarter that in living trees, how old is the sample?

Answer 1

k = 0.693/t_1/2
Then ln(No/N) = kt
If you call No 100 (as in 100%), then N will be 25%, you know k and you olve for t in years. Post your work if you get stuck.