What is the velocity of a photon?

$A$ photon is associated with .........

$A$ radio station broadcasts at a wavelength of $300 \ m$. If the radiating power of the transmitter is $10 \ kW$,then the number of photons emitted per second is:

The momentum of a photon of light of frequency $f$ is . . . . . . .

When light of wavelength $\lambda$ is incident on a photosensitive surface,photons of power $P$ are emitted. The number of photons $n$ emitted in time $t$ is: [$h$ = Planck's constant,$c$ = velocity of light in vacuum]

Light of wavelength $5000 \, \mathring{A}$ falls on a sensitive surface. If the surface has received $10^{-7} \, \text{J}$ of energy,then the number of photons falling on the surface will be: