About one carbon nucleus in a trillion contains two extra neutrons, giving a mass of 14.This carbon-14 is radioactive and decays with a half-life of 5730 years.
The half-life of a radioactive isotope (usually denoted by \(t_\)) is a more familiar concept than \(k\) for radioactivity, so although Equation \(\ref\) is expressed in terms of \(k\), it is more usual to quote the value of \(t_\).
There is an interesting case of a 33 year old Texas woman who enrolled in 10th grade in Texas.
She said she had no transcripts because she had been homeschooled. It also happened in the Little Leagues World Series, if I remember correctly.
Teeth from individuals with dates of birth ranging from 1936 through 1994 (aged 13–70 years) were analyzed, and where the date of birth was known, yielded a 14C-based Aspartic acid racemization also showed a good precision with an overall absolute error of 5.4 ± 4.2 years.
Whereas radiocarbon analysis gives an estimated year of birth, racemization analysis indicates the chronological age of the individual at the time of (tooth extraction).