According to the photon theory of light,which of the following physical quantities associated with a photon does not change as it collides with an electron in a vacuum?

If the wavelength of a photon is $4000 \text{ Å}$,then its energy will be

Monochromatic light of frequency $6 \times 10^{14} \text{ Hz}$ is produced by a laser. The power emitted is $4 \times 10^{-3} \text{ W}$. How many photons per second on an average are emitted by the source? $[h = 6.63 \times 10^{-34} \text{ Js}]$

The relationship between the velocity and frequency of a photon in a vacuum is represented by a ...... .

Consider the figure for photoemission. How would you reconcile this with the law of conservation of momentum? Note that light (photons) has momentum in a different direction than the emitted electrons.

An atom absorbs a photon of wavelength $500\,nm$ and emits another photon of wavelength $600\,nm$. The net energy absorbed by the atom in this process is $n \times 10^{-4}\,eV$. The value of $n$ is ............ [Assume the atom to be stationary during the absorption and emission process] (Take $h = 6.6 \times 10^{-34}\,Js$ and $c = 3 \times 10^8\,m/s$)