If a hydrogen atom is excited from the ground state to another state with a principal quantum number $n = 4$,the number of spectral lines in the emission spectrum will be:

An electron changes its position from orbit $n = 4$ to the orbit $n = 2$ of an atom. The wavelength of the emitted radiation is ($R =$ Rydberg's constant).

Write the Balmer formula in terms of the frequency of light.

The ratio of minimum to maximum wavelength in the Balmer series is

For a hydrogen atom,$\lambda_1$ and $\lambda_2$ are the wavelengths corresponding to the transitions $1$ and $2$ respectively,as shown in the figure. The ratio of $\lambda_1$ and $\lambda_2$ is $\frac{x}{32}$. The value of $x$ is $..........$

The wavelength of the second Balmer line in the hydrogen spectrum is $600 \ nm$. The wavelength for its third line in the Lyman series is: