where \(R_{0} \approx 1.2 \mathrm{Fm}\)

or \(R \propto(A)^{1 / 3}\)

\(\therefore \,\,\frac{{{R_{{\text{Bc}}}}}}{{{R_{{\text{Ge}}}}}} = \frac{{{{(9)}^{1/3}}}}{{{{(A)}^{1/3}}}}{\text{ }}\) or \(\frac{{{R_{{\text{Be}}}}}}{{2{R_{{\text{Be}}}}}} = \frac{{{{(9)}^{1/3}}}}{{{{(A)}^{1/3}}}}\)

( \(\because \) given \({R_{Ge}}\, = \,2{R_{Be}}\)) 

or, \((A)^{1 / 3}=2 \times(9)^{1 / 3}\) or, \(A=2^{3} \times 9=8 \times 9=72\)

\(\therefore\) The number of nucleons in \(Ge\) is \(72\)