An electron in the $n = 1$ orbit of a hydrogen atom is bound by $13.6\, eV$. The energy required to ionize it is........$ eV$.

The orbital acceleration of an electron is .........

If the radius of a hydrogen atom in its first orbit is $a_{0}$,then its radius in the third excited state is . . . . . . . (in $a_{0}$)

Angular momentum of an electron in a hydrogen atom is $\frac{3h}{\pi}$, then the energy of the electron is . . . . . . eV.

The ratio of the time periods of the revolution of the electrons in the second and third excited states of a hydrogen atom is

The total energy of an electron in the $n^{th}$ orbit of a hydrogen atom is $E_n$. The total energy of an electron in the $n^{th}$ orbit of a $He^+$ ion is .........