Moles of cu in 7.8 * 10^21 atoms of cu

Explanation:

According to mole concept, 1 mole of every substance contains atoms or molecules.

As number of atoms present in given copper are atoms. Therefore, calculate the number of moles present in this copper atom as follows.

       No.of moles =

                            =

                            = 0.0129 mol

Thus, we can conclude that there are 0.0129 moles of copper present in atoms.

radioactive decay occurs in unstable atomic nuclei – that is, ones that don't have enough binding energy to hold

the nucleus together due to an excess of either protons or neutrons.