Which of the following phenomena cannot be explained by the wave theory of light?

An important spectral emission line has a wavelength of $21 \ cm$. The corresponding photon energy is $(h = 6.62 \times 10^{-34} \ J \cdot s; \ c = 3 \times 10^8 \ m/s)$.

Which of the following particles has a mass similar to that of an electron?

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]

Which of the following is not a property of photons?

Monochromatic light of frequency $6 \times 10^{14} \,Hz$ is produced by a laser. The power emitted is $2 \times 10^{-3} \,W$. How many photons per second on an average are emitted by the source? (Given $h = 6.63 \times 10^{-34} \,Js$)