Question: What Is the Most Abundant Gas in the Earth's Atmosphere?
The Earth's atmosphere or air is composed of several gases. One gas is much more abundant than any other. Can you guess which one it is?
Answer: By far, the most abundant gas in the Earth's atmosphere is nitrogen, which accounts for about 78% of the mass of dry air. Oxygen is the next most abundant gas, present at levels of 20-21%. Although humid air seems like it contains a lot of water, the maximum amount of water vapor that air can hold is only about 4%.