According to the de broglie relation, the wavelength of a "matter" wave is inversely proportional to the momentum of the particle.

Yes the statement is correct

Explanation:

The de-broglie relation is mathematically represented as

where

p is momentum of the system

From the relation we can see that the wavelength is inversely proportional to the momentum of the particle.

that would be because of both gravity and friction. so     c

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.