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 practically independent of the atomic number for nuclei of mass number in the range 30 to 170.
Reason R : Nuclear force is short ranged.
In the light of the above statements, choose the correct answer from the options given below
Assertion A : The binding energy per nucleon is practically independent of the atomic number for nuclei of mass number in the range 30 to 170.
Reason R : Nuclear force is short ranged.
In the light of the above statements, choose the correct answer from the options given below
- (A)Both and are true but is NOT the correct explanation of
- (B) is true but is false
- (C) is false but is true
- (D)Both and are true and is the correct explanation of A✓ Correct
Answer: (D)
Solution
The binding energy per nucleon remains approximately constant (around 8 MeV) for nuclei with mass numbers between 30 and 170. This plateau occurs because the nuclear force is short-ranged — each nucleon interacts only with its nearest neighbors, not with all nucleons in the nucleus. As the nucleus grows, the number of nearest neighbors saturates, leading to a constant binding energy per nucleon. Thus, both statements are true and R correctly explains A.
JEE Main · 2023 · 13 Apr 2023 · Shift 2 · Single correct option