Which spectral series of the hydrogen atom is found in the ultraviolet region?

The wavelength of the first line of the Balmer series of a hydrogen atom is $\lambda \ \mathring{A}$. The wavelength of the same line for a doubly ionized lithium atom $(Z = 3)$ 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?

The ratio of the longest wavelength to the shortest wavelength observed in the five spectral series of the emission spectrum of hydrogen is

In the Balmer series,the wavelength of the first line is $\lambda_1$ and in the Brackett series,the wavelength of the first line is $\lambda_2$. Then,the ratio $\frac{\lambda_1}{\lambda_2}$ is:

Line spectra are due to