Which gas is most abundant in earth's atmosphere?
oxygen
nitrogen
water vapor
carbon dioxide

Answer;

Nitro.

Explanation:

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 to 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%.

Nitrogen.

Explanation:

Nitrogen may be defined as the element with the atomic number seven. The nitrogen is present in the earth in the form of free elements as well as in the combined state.

Nitrogen, the most abundantly presents in the earth. The nitrogen is present in the earth around 78%. The nitrogen is present in the earth's crust, in the environment and inside the body of living organism.

Thus, the correct answer is nitrogen.