Which of the following series of emission spectral lines for hydrogen is observed in the visible region?

The following sketch represents a specific wave of light. What will be the color of the light represented by this wave?

It is observed that characteristic $X$-ray spectra of elements show regularity. When frequency to the power '$n$' i.e.,$v^{n}$ of $X$-rays emitted is plotted against atomic number '$Z$',the following graph is obtained. The value of '$n$' is

The momentum (in $kg \cdot m/s$) of a photon having $6 \, MeV$ energy is:

What are the different regions of the electromagnetic spectrum?

The radiation is emitted when a hydrogen atom goes from a high energy state to a lower energy state. The wavelength of one line in the visible region of the atomic spectrum of hydrogen is $6.5 \times 10^{-7} \, m$. The energy difference between the two states is: