Which series of the hydrogen atom lie in the infrared region?

The difference in the wavelength between the maximum and minimum of Balmer series [Use $R_{H} = 1 \times 10^7 \ m^{-1}$]. (in $Å$)

$A$ doubly ionised $Li$ atom is excited from its ground state $(n = 1)$ to $n = 3$ state. The wavelengths of the spectral lines are given by $\lambda_{32}, \lambda_{31}$ and $\lambda_{21}$. The ratios $\lambda_{32}/\lambda_{31}$ and $\lambda_{21}/\lambda_{31}$ are,respectively:

The second line of the Balmer series has a wavelength of $4861 Å$. The wavelength of the first line of the Balmer series is: (in $Å$)

The electron in a hydrogen atom is initially in the second excited state. When it finally moves to the ground state, the maximum number of spectral lines emitted are:

The ratio of the longest to shortest wavelengths in the Brackett series of hydrogen spectra is