Physics - Modern Physics Question with Solution | TestHub

If$r_0$is radius of first orbit in Hydrogen atom then radius of first orbit in Hydrogen like atoms is given by$r=\frac{r_0}{Z}$.
For Hydrogen,$Z=1$
For Deuterium,$Z=1$
For singly ionized Helium$H{e}^{+}$,$Z=2$
For doubly ionized Lithium$L{i}^{2+}$,$Z=3$

$\therefore$Radius of the first orbit,$r$is minimum for doubly ionized Lithium.