Which of the following relations is correct for a photon?

Which of the following is true for a photon?

Write the equation for the energy of a photon.

The rest mass energy of an electron is $0.51 \ MeV$. If this electron is moving with a velocity of $0.8 \ c$ (where $c$ is the velocity of light in vacuum),then the kinetic energy of the electron is ........... $MeV$.

The wavelength of a $1 \;keV$ photon is $1.24 \times 10^{-9} \;m$. What is the frequency of a $1 \;MeV$ photon?

$A$ transmitter of $100 \ W$ power emits electromagnetic waves of wavelength $540 \ nm$. How many photons are emitted per second? (Given: $h = 6 \times 10^{-34} \ J \cdot s$,$c = 3 \times 10^8 \ m/s$)