How Does Helium Concentration Change with Height in a Cave?

[v_pino]

Homework Statement

In a large underground cave, the concentration of helium at the base is measured to be 1.00x10^-4. If the air in the cave is at a constant temperature of 10 degrees-C, what is the concentration of helium at the top of the cave, 300m higher?

Answer: 1.03 x 10^-4

Homework Equations

The Attempt at a Solution

Can someone please give me some hints as to approach this question? This is a question from a general paper, i.e. it can cover any topics in physics.

I thought about things like the Bernoulli's, but that's to do with fluid flow and in the question it doesn't mention speed.

Thanks.

 

[RocketSci5KN]

Some perceived graviational effect perhaps? I'm not even sure it would actually concentrate as the answer suggests in reality...