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

When an electron in a hydrogen atom jumps to the innermost orbit,the radiation emitted belongs to which one of the following series?

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

The first three spectral lines of the $H$-atom in the Balmer series are given as $\lambda_{1}, \lambda_{2}, \lambda_{3}$. Considering the Bohr atomic model,the wavelengths of the first and third spectral lines $\left(\frac{\lambda_{1}}{\lambda_{3}}\right)$ are related by a factor of approximately '$x$' $\times 10^{-1}$. The value of $x$,to the nearest integer,is:

Missing lines in a continuous spectrum reveal

$A$ hydrogen atom is excited from the ground state to a state with principal quantum number $n = 4$. The number of spectral lines emitted in the emission spectrum is: