What is the radius of fourth orbit of $\mathrm{Be}^{+++}$?
What is the radius of fourth orbit of $\mathrm{Be}^{+++}$?
$211.6 \mathrm{pm}$
$158.7 \mathrm{pm}$
$52.9 \mathrm{pm}$
$13.2 \mathrm{pm}$
Solution
$\mathrm{Be}^{+++}$is a hydrogen-like species having $\mathrm{Z}=4$. Radius of the fourth orbit of $\mathrm{Be}^{+++}$
$=\mathrm{r}_4=\frac{52.9 \times(4)^2}{4} \mathrm{pm}=211.6 \mathrm{pm}$