Atomic Mass Number and Stability – Rankers Physics

Nucleus: Practice Problem & Solution

Assertion (A): Atoms of greater mass number are more stable. Reason (R): Their mass defects are more.  
Both (A) & (R) are true and the (R) is the correct explanation of the (A)
Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
(A) is true but (R) is false
Both (A) and (R) are false

Solution Explained:

To solve this problem, we apply the core principles of Nucleus. Understanding the underlying formula is key to arriving at the correct answer below:

Nuclear stability depends on binding energy per nucleon, which peaks around \(A=56\). Very heavy nuclei are often unstable. So (A) is false. Total mass defect generally increases with mass number. So (R) is true.

Since (A) is false, options stating (A) is true are incorrect. With no 'A is false, R is true' option, (4) is selected due to question option constraints.

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