Question

The nuclear radius of a certain nucleus is $7.2\,fm$ and it has charge of $1.28\times 10^{- 17}C$ . The number of neutrons inside the nucleus is $\alpha ,$ then find the value of $\text{α.}\left(R_{0} = 1 . 2 \,fm\right)$

Answer 1

$7.2=1.2A^{1 / 3}$
$\Rightarrow A=6^{3}=216$
Now, $1.28\times 10^{- 17}=Z\times 1.6\times 10^{- 19}$
$\Rightarrow \frac{128}{1 . 6}=Z=80$
$\Rightarrow N=A-Z=136$