Carbon dating radioactive
When an organism dies it ceases to replenish carbon in its tissues and the decay of carbon 14 to nitrogen 14 changes the ratio of carbon 12 to carbon 14.Experts can compare the ratio of carbon 12 to carbon 14 in dead material to the ratio when the organism was alive to estimate the date of its death.However, open-air nuclear testing between 1955–1980 contributed to this pool.
So, scientists can estimate the age of the fossil by looking at the level of decay in its radioactive carbon.
We can use the same idea to find out how long it would take for a sample with radioactivity 120 Bq to drop to 30 Bq. We can use radioactive decay to calculate the age of things.
The best-known technique is called ‘radiocarbon dating’ or just 'carbon dating'.
Carbon dating can only be used to find the age of things that were once alive, like wood, leather, paper and bones.
If you have a wooden box, carbon dating can tell you when the tree to make it was cut down but not when the box was made. Carbon dioxide is made into simple sugars and it is these that are the building blocks that make up wood, bark and leaves.