Question

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:

• A. (A) is false but (R) is true
• B. (A) is true but (R) is false
• C. Both (A) and (R) are true and (R) is the correct explanation of (A)
• D. Both (A) and (R) are true but (R) is NOT the correct explanation of (A)

Hint:

The nuclear force is short-range, and while binding energy per nucleon is nearly constant for a wide range of atomic numbers, it is not due to the nuclear force being long-range.

Answer 1

The Correct Option is B

Assertion (A) is true. The binding energy per nucleon for most nuclei with mass numbers between 30 and 170 remains approximately constant because the nuclear force is nearly the same for all these nuclei. - Reason (R) is false. The nuclear force is actually a short-range force, typically acting over distances of about 1 to 2 femtometers (fm), which is much shorter than the range of electromagnetic forces. Thus, the correct answer is (2), where Assertion (A) is true, but Reason (R) is false.