AIIMS2017Physics-Nuclear Physics

AIIMS 2017 Physics Radioactive Decay Assertion Reason Question

Type: Assertion Reason-conceptual-Medium-Class 12

In the following questions, a statement of assertion is given followed by a corresponding statement of reason. Assertion: In a decay atom number of daughter nucleus reduces by 2 from the parent nucleus. Reason: An Q⁻particle carries four units of mass.

A

If both assertion and reason are true and reason is correct explanation of assertion.

B

If both assertion and reason are true and reason is not correct explanation of assertion.

C

If assertion is true but reason is false.

D

If both assertion and reason are false.

Correct Answer

Option B

Detailed Explanation

Option B is correct because the assertion states that in a decay process, the atomic number of the daughter nucleus decreases by 2, which is true for alpha decay, where an alpha particle (⁴₂He) is emitted. However, while the reason is also true—an alpha particle does indeed carry four units of mass—it does not directly explain why the atomic number decreases by 2, as the mass number and atomic number are distinct properties.

Option A is incorrect because, although both statements are true, the reason does not adequately explain the assertion. Option C is incorrect since the assertion is true, and the reason is true as well. Option D is incorrect because both statements are true.

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