Question

If r1 and r2 are the radii of the atomic nuclei of mass numbers 64 and 125 respectively, then the ratio $ \left( {{r}_{1}}/{{r}_{2}} \right) $ is

• A. $ \frac{64}{125} $
• B. $ \sqrt{\frac{64}{125}} $
• C. $ \frac{5}{4} $
• D. $ \frac{4}{5} $

Answer 1

Answer: (D)

$ r={{r}_{0}}{{(A)}^{1/3}} $ $ \therefore $ $ \frac{{{r}_{1}}}{{{r}_{2}}}={{\left( \frac{A{{ & }_{1}}}{{{A}_{2}}} \right)}^{1/3}} $ $ ={{\left( \frac{64}{125} \right)}^{1/3}} $ $ ={{\left[ {{\left( \frac{4}{5} \right)}^{3}} \right]}^{1/3}}=\frac{4}{5} $