Multiple choice

What happens to oxygen molecules at high altitudes?

  1. spread out

  2. increase

  3. decrease

  4. disappear

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

As altitude increases, atmospheric pressure decreases, causing gas molecules, including oxygen, to spread out and become less dense. While the percentage of oxygen remains about 21%, there are fewer molecules in any given volume of air.