What is the maximum wavelength line in the Lyman series of $He^{+}$ ion?

If the radius of the second Bohr orbit of the $He^{+}$ ion is $105.8 \, pm$, what is the radius of the third Bohr orbit of the $Li^{2+}$ ion?

The energy required to dislodge an electron from an excited isolated $H^-$ ion,given that the ionization energy of a ground state $H$ atom is $IE_1 = 13.6 \ eV$,is:

Describe the hydrogen spectrum.

Which of the following statements are correct?
$I$) The energy of hydrogen atom in its ground state is $-13.6 \ eV$
$II$) On the basis of Bohr's model,the radius of the $3^{rd}$ orbit of hydrogen atom is $158.7 \ pm$
$III$) The order of radius of the first orbit of $H, He^{+}, Li^{2+}$ and $Be^{3+}$ is $H > He^{+} > Li^{2+} > Be^{3+}$

With increasing principal quantum number,the energy difference between adjacent energy levels in $H$ atom