What is the main ingredient in air?

Answer 1

If by "main ingredient", you mean the substance that comprises the largest percentage of the volume of the earth's atmosphere, the answer is Nitrogen, specifically the N2 molecule, comprising about 78.1% of the volume (and 75.3% of the weight) of the earths' atmosphere.

Answer 2

By volume it is nitrogen.

Nitrogen form ~ 79%

Oxygen forms ~ 20%

The remaing 1% is composed of water vapour, carbon dioxide, methane, ammonia, sulphur dioxide, nitrogen dioxide, and the noble(inert) gases.

Although, humans live in 'fear and trembling' on the level of carbon dioxide in the atmopsphere, it is actually extremely low, by volume, compenent of the atmosphere.

Answer 3

The main ingredient in air is nitrogen, which makes up about 78% of the Earth's atmosphere. Oxygen is the second most abundant component, at around 21%. Other gases such as carbon dioxide, argon, and trace amounts of other gases make up the rest.