The electronic energy levels of the hydrogen atom in the Bohr's theory are called

The radius of the second Bohr orbit is $x$. The de-Broglie wavelength of an electron in the $4^{th}$ orbit is nearly

The Balmer series in the hydrogen spectrum corresponds to the transition from $n_1 = 2$ to $n_2 = 3, 4, ...$ This series lies in the visible region. Calculate the wave number of the line associated with the transition in the Balmer series when the electron moves to the $n = 4$ orbit. $(R_H = 109677 \ cm^{-1})$

The ionisation potential of a hydrogen atom is $-13.6 \ eV$. What will be the energy of the atom corresponding to $n = 2$?

If the work function of a metal is $6.63 \times 10^{-19} \ J$,the maximum wavelength of the photon required to remove a photoelectron from the metal is $.... \ nm$. (Nearest integer)
[Given : $h = 6.63 \times 10^{-34} \ J \ s$,and $c = 3 \times 10^{8} \ m \ s^{-1}$ ]

If an electron in a hydrogen atom undergoes a transition from the $4^{th}$ stationary orbit and emits a line in the Lyman series,calculate the wavelength of the emitted radiation.