Why does oxygen has a greater force of attraction between its particles than nitrogen? PLEASE HELP!

Because it is more electronegative than nitrogen.

Explanation:

Oxygen has greater force of attraction between it's Molecules than nitrogen because it is more electronegative than nitrogen and this is because it has more slightly charged positive protons in it's electrons and thus make it slightly negative in it's nucleus. It has 8 electrons in it's nucleus compare to 7 electrons nitrogen has and this will make a bonding pair to occur in oxygen than nitrogen.

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.