If the ionisation energy for the hydrogen atom is $13.6$ eV, then the energy required to excite it from the ground state to the next higher state is nearly (in $eV$)

Energy of an electron in the second orbit of a hydrogen atom is $E_{2}$. The energy of an electron in the third orbit of $He^{+}$ will be

The energy of a hydrogen atom in its ground state is $-13.6 \ eV$. The energy of the level corresponding to the quantum number $n = 2$ (first excited state) in the hydrogen atom is......$eV$.

$A$ $12.5 \ eV$ electron beam is used to bombard gaseous hydrogen at room temperature. It will emit:

The ratio of the energies of the hydrogen atom in its first to second excited state is

$A$ difference of $5.4 \ eV$ separates two energy levels in an atom. What is the frequency of radiation emitted when the atom makes a transition from the upper level to the lower level? (Take $1 \ eV = 1.6 \times 10^{-19} \ J$,$h = 6.625 \times 10^{-34} \ Js$)