Question

When the number of nucleons in nucleus increase, the binding energy per nucleon first _________ and then _________ with increase of mass number.

Answer 1

When the number of in nucleus increases, the binding energy per nucleon first increases because high binding energy is required to separate a stable nucleus into its constituent protons and neutrons. When the mass number is increasing the binding energy per nucleon gradually decrease. So there is misufficient binding energy to hold the nucleus together.