In the case of a hydrogen atom,when an electron falls from a higher energy level to the $M$ shell,the corresponding spectral line will form a part of:

What is the energy of an electron in the stationary state corresponding to $n=2$?

When light is directed at the metal surface,the emitted electrons

When electromagnetic radiation of wavelength $310 \ nm$ falls on the surface of a metal having work function $3.55 \ eV$, the velocity of photoelectrons emitted is $x \times 10^5 \ ms^{-1}$. The value of $x$ is (Nearest integer). Given: $m_{e} = 9 \times 10^{-31} \ kg$, $h = 6.63 \times 10^{-34} \ J \cdot s$, $c = 3 \times 10^8 \ m/s$, $1 \ eV = 1.6 \times 10^{-19} \ J$.

The wavelength of a spectral line emitted by a hydrogen atom in the Lyman series is $\frac{16}{15 R} \ cm$. What is the value of $n_2$? $(R = \text{Rydberg constant})$

When a certain metal was irradiated with light of frequency $4.0 \times 10^{16} \ s^{-1}$,the photoelectrons emitted had four times the kinetic energy as the kinetic energy of photoelectrons emitted when the same metal was irradiated with light of frequency $2.0 \times 10^{16} \ s^{-1}$. The threshold frequency $(v_0)$ of the metal in $s^{-1}$ is