What is the Significance of binding energy per nucleon vary with mass number?

The binding energy per nucleon varies with mass number because it represents the average energy required to separate a nucleus into its individual nucleons. For lighter nuclei, the binding energy per nucleon increases as the nucleus becomes more stable. As nuclei become larger (higher mass number), the binding energy per nucleon decreases due to the diminishing strength of the nuclear force relative to the electrostatic repulsion between protons.