Which scientist discarded the postulate of ether?

If $h$ is Planck's constant,the momentum of a photon with a wavelength of $0.01 \ \mathring A$ is .........

$A$ bulb lamp emits light of mean wavelength of $4500 \mathring A$. The lamp is rated at $150 \text{ W}$ and $8 \%$ of the energy appears as emitted light. How many photons are emitted by the lamp per second?

There are $n_1$ photons of frequency $\nu_1$ in a beam of light. In an equally energetic beam,there are $n_2$ photons of frequency $\nu_2$. Then the correct relation is

Which of the following is not a property of photons?

$A$ photon in motion has a mass.