The energy of $He^{+}$ ion in its first excited state is $......eV$ (The ground state energy for the Hydrogen atom is $-13.6\,eV$).

The radius of the first orbit in a hydrogen atom is $5.3 \times 10^{-11} \text{ m}$. The kinetic energy $E_K$, potential energy $E_P$, and total energy $E_T$ of the electron in the first orbit are:

Consider an electron revolving in a circular orbit of a hydrogen atom,whose quantum number is $n=2$. The velocity of the electron in that orbit is

Electrons in a certain energy level $n=n_{1}$ can emit $3$ spectral lines. When they are in another energy level $n=n_{2}$,they can emit $6$ spectral lines. The orbital speed of the electrons in these orbits are in the ratio:

In a hydrogen atom, the electron makes $6.6 \times 10^{15}$ revolutions per second around the nucleus in an orbit of radius $0.5 \times 10^{-10} \, m$. This is equivalent to a current of nearly:

In the Bohr model of the hydrogen atom,the force on the electron is proportional to which power of the principal quantum number $n$?