(c) $r \propto A^{1/3} \Rightarrow \frac{r_{1}}{r_{2}} = \left( \frac{A_{1}}{A_{2}} \right)^{1/3}$ $\Rightarrow \frac{3.6}{r_{2}} = \left( \frac{27}{125} \right)^{1/3} = \frac{3}{5} \Rightarrow r_{2} = 6\ fermi$
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.