Given below are two statements. One is labelled as Assertion (A) and the other is labelled as Reason (R).
**Assertion (A):** The binding energy per nucleon is found to be practically independent of the atomic number $A$, for nuclei with mass numbers between 30 and 170.
**Reason (R):** Nuclear force is long range.
In the light of the above statements, choose the correct answer from the options given below:
Answer: (A) (A) is true but (R) is false
**(A)** The binding energy per nucleon curve is nearly flat (about $8$–$8.8\ \text{MeV}$) for mass numbers roughly 30 to 170. True.
**(R)** The nuclear force is **short range** (a few femtometres). This is actually why the curve saturates: each nucleon interacts only with its nearest neighbours. False.
Solution by Sreeraj P, M.Sc Physics