Naturally occurring carbon has the isotopic composition C-12, 98.89%; C-13, 1.11% and traces of C-14. The carbon dating technique is used to determine the ages of biological artifacts up to 50000 years old. C-14 provides the basis for this dating technique.

C-14 is produced in the upper atmosphere by slow neutron capture by nitrogen atom & decays by beta-negative emission with half-life of 5730 years.

There are a few categories of artifacts have the ages within 50000 years. These can only be dated using C-14. Also, C-14 can not be used to date biological artifacts of organisms that did not get their carbon dioxide from the air. This rules out carbon dating for most aquatic organisms.

The isotope with longer half-life (1.3 billion years), such as potassium-40 (found in greater abundance in older fossils) can determine the age of older fossils. These methods of carbon dating have been well calibrated using objects of known ages, and the uncertainties are of the order of 5% of the age.

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