The energy of the second Bohr orbit of the hydrogen atom is $-3.4 \ eV$. The energy of the fourth Bohr orbit of the $He^{+}$ ion will be: (in $eV$)

The energy of an electron in the first Bohr orbit of a hydrogen atom is $-13.12 \times 10^5 \ J \ mol^{-1}$. Calculate the energy required for the transition of an electron from the first orbit to the second orbit.

What will be the ionization energy in $eV$ for an excited hydrogen atom?

The radius of the first orbit of $Li^{2+}$ is $X \mathring{A}$. The radius of the third orbit of $He^{+}$ (in $\mathring{A}$) is (in $X$)

The wavenumber of the first spectral line of the Lyman series of $He^{+}$ ion is $x \ m^{-1}$. What is the wavenumber (in $m^{-1}$) of the second spectral line of the Balmer series of $Li^{2+}$ ion?

The ionization energy of a hydrogen atom is $13.6 \ eV$. The energy required to ionize a hydrogen atom in its second excited state is ........... $eV$.