How do we compute the age of a rock ?

Explanation

The age of rock is year is called its absolute age. It is determined by the natural radioactive decay of certain elements, e.g., uranium, when decays turns into lead. The parent atoms of uranium are converted into daughter atoms of lead over fixed interval of time. This interval is the decay constant.
The ratio of parent-daughter atoms changes in a quantity that can be measured.
The radioactive half-life ( the amount of time required for one half of the parent atoms to beonverted to daughter atoms ) is used to calculate tha age of the rock.