Chemistry - Mole Concept Question with Solution | TestHub

For hydrogen like atom, the radius of n^th orbit is given by,

${\mathrm{r}}_{\mathrm{n}}=\frac{{\mathrm{n}}^2}{\mathrm{Z}}{\mathrm{r}}_0$

Where, ${\mathrm{r}}_0=0.53\times {10}^{-10} \mathrm{m}$

and ${\mathrm{r}}_{\mathrm{n}}=\frac{0.53\times {10}^{-10} \mathrm{m}}{4}$

At ground state, $\mathrm{n}=1$ 

Hence, the atom is ${\mathrm{Be}}^{3+}$ $[\because \mathrm{Z}=4]$

So, the atom is triply ionised beryllium ${\mathrm{Be}}^{3+}$.