In an atom, the difference between two energy levels is $3.31 \ eV$. The wavelength of the radiation emitted when the transition takes place between these levels is nearly: (in $Å$)

When a hydrogen atom is raised from the ground state to an excited state,

Assertion : Between any two given energy levels,the number of absorption transitions is always less than the number of emission transitions.
Reason : Absorption transitions start from the lowest energy level only and may end at any higher energy level. But emission transitions may start from any higher energy level and end at any energy level below it.

If the binding energy of the electron in a hydrogen atom is $13.6 \ eV$,the energy required to remove the electron from the first excited state of $Li^{++}$ is.....$eV$.

Which fact indicates that the total energy of an electron in an atom is negative?

The total energy of an electron in an orbit of a hydrogen atom is $E$. The potential energy of the electron in the same orbit is: