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?

Consider two black bodies $A$ and $B$ having equal surface areas. On the surface of $A$,$n$ photons of frequency $f$ are incident perpendicularly in a time $t$. On the surface of $B$,$2n$ photons of frequency $3f$ are incident perpendicularly in a time $4t$. The ratio of average intensity of radiation on surface $A$ to that on surface $B$ is

If the wavelength of an $X-ray$ is $0.010 \ \mathring A$,what is its momentum?

$n$ photons of wavelength $\lambda$ are absorbed by a black body of mass $m$. The momentum gained by the body is

An electron and a proton are detected in a cosmic ray experiment,the first with kinetic energy $10 \; keV$,and the second with $100 \; keV$. Which is faster,the electron or the proton? Obtain the ratio of their speeds. (Electron mass $= 9.11 \times 10^{-31} \; kg$,proton mass $= 1.67 \times 10^{-27} \; kg$,$1 \; eV = 1.60 \times 10^{-19} \; J$)

The wavelength of an electron and a photon are equal. If the energy of the photon is $E$ and the momentum of the electron is $p$,what is the value of $p/E$?