The nuclei inside the nucleus are very strongly bound and energies of few MeV are needed to separate a nucleon from the nucleus. Hence, a minimum energy is required to split the protons and neutrons and that energy is known as the binding energy of the nucleus. If, there are Z number of protons and N number of neutrons and mass of the nucleus is M(A,Z), then binding energy EB=ZmpC2+NmnC2−M(A,Z)C2>0, where mp and mn are the masses of protons and neutrons, respectively. Hence, we can conclude that, the mass of the nucleus must be less than the sum of the masses of the constituent neutrons and protons.