Carbon-14 dating is rarely useful for specimens older than about years

PHYSICS · Single correct · A Level · Physics · Nuclear physics · Nuclear physics

Problem

Carbon-14 dating is rarely useful for specimens older than about

5\times10^{4}\,

years. Which of the following best explains this limitation? (a) Cosmic rays completely stop producing

^{14}\text C

after

5\times10^{4}\,

years have elapsed. (b) After such a long time the remaining

^{14}\text C

activity becomes too low to measure accurately. (c) The

\beta

particles from

^{14}\text C

decay are fully absorbed by the specimen after about

5\times10^{4}

years, so detectors cannot register them. (d) The half-life of

^{14}\text C

increases with the age of the sample, giving unreliable results.