What method can scientists use to determine the absolute age of a rock?

There possible way of finding the age of fossils/rock is radioactive dating

Explanation:

Elements may exist in different isotopic forms. For example C-12 and C-14 are the isotopes of C element. Now C-14 is a radioactive isotope and we know that naturally occurring unstable radioactive isotopes decay over the course of time. The rate is given by the half life of that radioactive isotope, usually given in units of years. We can calculate the ratio of observed abundance of that radioactive isotope and its decay product in the rock we are studying. This is the principle of radioactive dating.

enzyme active site and substrate specificity

enzymes bind with chemical reactants called substrates. there may be one or more substrates for each type of enzyme, depending on the particular chemical reaction. in some reactions, a single-reactant substrate is broken down into multiple products