The radius of ${ }_{72} \mathrm{Te}^{125}$ nucleus is 6 fermi. The radius of ${ }_{13} \mathrm{Al}^{27}$…

The radius of ${ }_{72} \mathrm{Te}^{125}$ nucleus is 6 fermi. The radius of ${ }_{13} \mathrm{Al}^{27}$ nucleus in meters is
  1. $3.6 \times 10^{-12} \mathrm{~m}$
  2. $3.6 \times 10^{-15} \mathrm{~m}$
  3. $7.2 \times 10^{-8} \mathrm{~m}$
  4. $7.2 \times 10^{-15} \mathrm{~m}$

Solution

The relation between radius $(R)$ and atomic number $(A)$ is $\frac{R_1}{R_2}=\left(\frac{A_1}{A_2}\right)^{1 / 3}$ Given, $R_1=6$ fermi, $A_1=125, A_2=27$ $\begin{aligned} \frac{6}{R_2} & =\left(\frac{125}{27}\right)^{1 / 3}=\frac{5}{3} \\ \Rightarrow R_2 & =\frac{6 \times 3}{5}=\frac{18}{5}=3.6 \text { fermi } \\ & =3.6 \times 10^{-15} \mathrm{~m} \end{aligned}$

Asked in: AP EAMCET 2013

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