Question

The reason for the constancy of binding energy per nucleon of nuclei whose mass number lies between 30 and 170 is

• A. Short range of nuclear forces
• B. The nuclear force between neutron-neutron is greater than the nuclear force between proton-proton
• C. Nuclear forces are weak forces
• D. Binding energy per nucleon is lower for these nuclei

Hint:

The saturation property of nuclear force is responsible for the nearly constant value of binding energy per nucleon for medium mass nuclei.

Answer 1

The Correct Option is A

Concept: The binding energy per nucleon remains nearly constant for medium mass nuclei because nuclear forces are short-ranged and saturating in nature. Each nucleon interacts only with a few nearest neighbours.

Step 1: Understand the nature of nuclear forces.
Nuclear forces act only over very small distances of the order of \[ 10^{-15}m \] Therefore, a nucleon cannot interact with all other nucleons in the nucleus.

Step 2: Apply the saturation property.
Since each nucleon interacts only with nearby nucleons, the binding energy contributed by each nucleon remains approximately the same. Hence, \[ \frac{BE}{A} \] remains nearly constant.

Step 3: State the answer.
Therefore the correct reason is \[ \boxed{\text{Short range of nuclear forces}} \]