Which one of the series of hydrogen spectrum is in the visible region?

The spectral series of the hydrogen atom that lies in the visible region of the electromagnetic spectrum is:

If the series limit of the Lyman series for a Hydrogen atom is equal to the series limit of the Balmer series for a hydrogen-like atom,then the atomic number of this hydrogen-like atom will be:

When the electron in the hydrogen atom jumps from the $2^{nd}$ orbit to the $1^{st}$ orbit,the wavelength of the radiation emitted is $\lambda$. When the electron jumps from the $3^{rd}$ orbit to the $1^{st}$ orbit,the wavelength of the emitted radiation will be:

If $R$ is the Rydberg constant in $cm^{-1}$, then the hydrogen atom does not emit any radiation of wavelength in the range of

Hydrogen atoms are excited from the ground state to the principal quantum number $n = 5$. The number of spectral lines observed will be: