Which series is found in the visible light region?

In the Balmer series,the wavelength of the $2^{\text{nd}}$ line is $\lambda_1$ and for the Paschen series,the wavelength of the $1^{\text{st}}$ line is $\lambda_2$. Then the ratio $\lambda_1 : \lambda_2$ is:

In hydrogen spectrum,which of the following spectral series lies in the ultraviolet region?

Ionisation potential of hydrogen atom is $13.6 eV$. When hydrogen atoms in ground state are excited by a supply of $12.1 eV$,then the number of spectral lines emitted by hydrogen atoms according to Bohr's theory is

In a hydrogen atom,the wavelength of the light emitted during a transition from the $n = 3$ orbit to the $n = 2$ orbit is ${\lambda _0}$. What will be the wavelength of the light emitted during a transition from the $n = 4$ orbit to the $n = 2$ orbit?

What is the wave number of the lowest energy transition associated with the Paschen series?