$A$ hydrogen atom is excited from the ground state to a state with principal quantum number $n = 4$. The number of spectral lines emitted in the emission spectrum is:

If the electron in a hydrogen atom transits from the second orbit to the first orbit,in what region would the emitted radiation be?

If Rydberg's constant is $R$,the longest wavelength of radiation in Paschen series will be $\frac{\alpha}{7 R}$,where $\alpha=$ . . . . . .

The wavelength of the first spectral line in the Balmer series of a hydrogen atom is $6561 \mathring A$. The wavelength of the second spectral line in the Balmer series of a singly-ionized helium atom is

What is the shortest wavelength present in the Paschen series of spectral lines (in $;nm$)?

The shortest wavelength of the spectral lines in the Lyman series of the hydrogen spectrum is $915 \text{ Å}$. The longest wavelength of spectral lines in the Balmer series will be: (in $\text{ Å}$)