Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.
**Assertion A:** The nuclear density of nuclides $^{10}_{5}\text{B}$, $^{6}_{3}\text{Li}$, $^{56}_{26}\text{Fe}$, $^{20}_{10}\text{Ne}$ and $^{209}_{83}\text{Bi}$ can be arranged as $\rho^N_{Bi}>\rho^N_{Fe}>\rho^N_{Ne}>\rho^N_{B}>\rho^N_{Li}$.
**Reason R:** The radius $R$ of nucleus is related to its mass number $A$ as $R=R_0A^{1/3}$, where $R_0$ is a constant.
In the light of the above statements, choose the correct answer from the options given below:
Answer: (B) A is false but R is true
With $R=R_0A^{1/3}$, nuclear volume $\propto A$, so density $=\dfrac{Am}{\frac43\pi R_0^3A}$ is the same for all nuclei. R is true and shows that A (an ordering of densities) is false.
Solution by Sreeraj P, M.Sc Physics