What is the momentum of a photon that has a wavelength of 3.00 102 nm? remember the wavelength of a photon is equal to planck's constant divided by the photon's momentum?

De Broglie's equation is used to show that photons have both particle and wave nature. photons are quantized packets of energy. the wave nature of photons can be proven as they have a wavelength. the particle nature is given by them having both velocity and mass. 
de Broglies equation is;
λ = h / p 
where λ - wavelength 
h - Planck's constant 
p - momentum 
substituting the values in the equation 
p = h/λ

p  = 2.20 x 10⁻²⁷ kgm/s
momentum of photon is 2.20 x 10⁻²⁷ kgm/s