JEE Mains · Physics · STD 12 - 13. Nuclei
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : The density of the copper \(\left({ }_{29}^{64} \mathrm{Cu}\right)\) nucleus is greater than that of the carbon \(\left({ }_6^{12} \mathrm{C}\right)\) nucleus.
Reason (R): The nucleus of mass number A has a radius proportional to \(\mathrm{A}^{1 / 3}\).
In the light of the above statements, choose the most appropriate answer from the options given below :
- A \((\mathrm{A})\) is correct but \((\mathrm{R})\) is not correct
- B \((\mathrm{A})\) is not correct but \((\mathrm{R})\) is correct
- C Both \((\mathrm{A})\) and \((\mathrm{R})\) are correct and \((\mathrm{R})\) is the correct explanation of (A)
- D Both (A) and (R) are correct but (R) is not the correct explanation of (A)
Answer & Solution
Correct Answer
(B) \((\mathrm{A})\) is not correct but \((\mathrm{R})\) is correct
Step-by-step Solution
Detailed explanation
\(\rho=\frac{\mathrm{M}}{\mathrm{~V}}=\frac{\mathrm{m}_{\mathrm{n}} \times \mathrm{A}}{\frac{4}{3} \pi \mathrm{R}^3}=\frac{\mathrm{m}_{\mathrm{n}} \times \mathrm{A}}{\frac{4}{3} \pi \mathrm{AR}_0^3}\) So \(\rho\) is almost is constant…
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