if nitrogen is lighter than oxygen then why it doesn`t accumulate at upper atmosphere?

Answer 1

think like its water lighter than floats right

Answer 2

The density of nitrogen is about 12% less than that of oxygen. This does cause nitrogen to tend to rise relative to the oxygen in air.

However, other forces that facilitate the mixing of oxygen and nitrogen have a much greater effect. These forces include microscopic effects (in particular, diffusion, the tendency of the individual molecules to move randomly among each other) and large-scale effects (motion of the air caused by temperature differences or pressure differences ... winds and updrafts/downdrafts).

Consequently, there is no significant difference in the proportions of nitrogen and oxygen in air at different altitudes.

Answer 3

the rate of movement based on weight is very slow. while something that is much less dense than water will rise quickly (like a buoy), this isn't the case in air. the motion that wind gives to the air in the atmosphere is much more than the motion that a difference in density would.

also O2 and N2 are only different by ~6% of O2's mass.

Answer 4

you should consider diffusion
particles tend to move from area of higher concentration to the lower. This is due to probability law; particles tends to have same concentratione every where
as the weight difference between O2 and N2 is not too big (~10%), diffusion plays important role rather than gravitation

Answer 5

The answe is simply mixture and winds. I read a while back about a extinct volcano somewhere that the inside of the cone feels no wind, and they did actually see elevated levels of heavy gases such as argon.

Answer 6

Sounds like you need to study more science....I mean the general science like that they teach in High School.

Answer 7

Because it readily mixes with other elements?