Question

The radius of germanium ( $Ge$ ) nuclide is measured to be twice the radius of $_{4}^{9} \text{Be} \text{.}$ Calculate the number of nucleons in $Ge$ .

Answer 1

Nuclear radius, $R=R_{0}(A$,
or $R \propto(A$
$\frac{R_{ Be }}{R_{ Ge }}=\frac{(9)^{1 / 3}}{(A)^{1 / 3}} \quad$ or, $\quad \frac{R_{ Be }}{2 R_{ Be }}=\frac{(9)^{1 / 3}}{(A)^{1 / 3}} \quad\left(\because\right.$ Given $\left.R_{ Ge }=2 R_{ Be }\right)$
or $(A=2 \times(9$
or $A=2^{3} \times 9=8 \times 9=72$
$\therefore$ The number of nucleons in $Ge$ is 72 .