CBSE Class 9 Answered

 To measure the amount of radiocarbon left in a articaft,scientists burn a small piece to convert it into carbon di oxide gas.Radiation counters are used to detect the electrons given off by decaying C-14 as it turns intio nitrogen. In order to date the articaft, the amount of C-12( the stable form of carbon) to determine how much radiocarbon has decayed. The ratio of C_12 to C_14 is the same in all the living things.However at the moment of death, the amount of C-14 begins to decrease because it is unstable, while the amount of C-12 remains constant in the sample..Half of the c-14 degrades every 5,730 years as indicated by its half life. By measuring the ratio of C-12 to C-14 in the sample and comparing it to the ratio in a living organism, it is possible to determine the age of the articaft.