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

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

The light emitted in the transition $n = 3$ to $n = 2$ (where $n$ is the principal quantum number of the state) in hydrogen is called $H_{\alpha}$-light. Find the maximum work function that a metal can have so that $H_{\alpha}$-light can emit photoelectrons from it. (in $\text{ eV}$)

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:

An electron jumps from the $4^{\text{th}}$ orbit to the $2^{\text{nd}}$ orbit of a hydrogen atom. Given Rydberg's constant $R_{H}=10^7 \ m^{-1}$,calculate the frequency in $Hz$ of the emitted radiation. (Take $c=3 \times 10^8 \ m/s$)

The spectral series observed for the hydrogen atom found in the visible region is