Question

The binding energy per nucleon initially increases and then decreases with mass number because:

• A. The force of attraction between nucleons increases initially and then decreases.
• B. The strong nuclear force between nucleons increases with mass number.
• C. The size of the nucleus increases with mass number, leading to decreased binding energy per nucleon.
• D. The weak nuclear force has no significant effect on the binding energy.

Answer 1

The Correct Option is C

The binding energy per nucleon is a measure of the stability of a nucleus. Initially, as the mass number increases, the binding energy per nucleon increases due to the increased strong nuclear force, which effectively binds the nucleons together. However, as the nucleus becomes larger with increasing mass numbers, the effect of the strong force diminishes over longer ranges, and the repulsive electrostatic forces between protons become more significant.

Consequently, this leads to a decrease in binding energy per nucleon because the attractive forces are less able to counteract the repulsive forces. Thus, the binding energy curve first rises with lighter elements and begins to decrease as the atomic number becomes larger. The correct explanation is:

The size of the nucleus increases with mass number, leading to decreased binding energy per nucleon.