Which of the following series of transitions in the spectrum of hydrogen atom falls in the visible region?

Explain Bohr's atomic model.

Calculate the energy and frequency of the radiation emitted when an electron jumps from $n = 3$ to $n = 2$ in a hydrogen atom.

The angular momentum of an electron in an $H$ atom in a particular $n$ state is $\frac{h}{\pi}$. What is the energy in $J$ required to excite the electron from this particular $n$ state to $(n+1)$ state? $(x = 2.18 \times 10^{-18} \ J)$

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 $c = 3 \times 10^{8} \ m \ s^{-1}$ ]

The figure that is not a direct manifestation of the quantum nature of atoms is: