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 $Å$)

The ratio of the energies of the electron in the hydrogen atom in the first and second excited states is

An electron of a stationary hydrogen atom transits from the fourth energy level to the ground level. The velocity of the hydrogen atom acquired as a result of photon emission will be:
{ $R =$ Rydberg constant,$m =$ mass of hydrogen atom }

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 ......... $eV$.

If $n$ is the orbit number of the electron in a hydrogen atom,the correct statement among the following is

During the transition of an electron from state $A$ to state $C$ of a Bohr atom,the wavelength of the emitted radiation is $2000 \ \mathring A$ and it becomes $6000 \ \mathring A$ when the electron jumps from state $B$ to state $C.$ Then the wavelength of the radiation emitted during the transition of electrons from state $A$ to state $B$ is