The minimum energy required to excite a hydrogen atom from its ground state is.....$ eV$.

Which of the following transitions in hydrogen atoms emit photons of highest frequency?

An electron collides elastically with an $H$-like atom and excites it from the ground state to $n = 3$. Find the energy transferred to the $H$-like atom in $eV$.

The energy of a hydrogen atom in the $n^{th}$ orbit is $E_n$. What will be the energy in the $n^{th}$ orbit of a singly ionized helium atom?

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 $Å$)

$A$ hydrogen atom initially in the ground level absorbs a photon,which excites it to the $n = 4$ level. Determine the wavelength and frequency of the photon.