If an electron in a hydrogen atom undergoes a transition from the $4^{th}$ stationary orbit and emits a line in the Lyman series,calculate the wavelength of the emitted radiation.

In an electron transition from an infinite state to the ground state in an $H$ atom,find the emitted wavelength. (in $nm$)

In a mixture of $H$ and $He^{+}$ gases,all $H$ atoms and $He^{+}$ ions are excited to their first excited states. Subsequently,on de-excitation in $H$ atoms,energy is transferred to the excited $He^{+}$ ion. The quantum number $n$ of the $He^{+}$ ion after the energy is transferred is:

The visible range of the hydrogen spectrum contains which of the following series?

Which of the following represents the wavelength of a spectral line of the Balmer series of the $He^{+}$ ion? ($R=$ Rydberg constant,$n > 2$)

The frequency of a line in the Pfund series of a hydrogen atom is $2.340 \times 10^{14} \ Hz$. The value of the quantum number $n_2$ for this transition is .....