Question: how is air made

Martin McCoustra answered on 13 Mar 2024:

When the Earth was formed, the atmosphere was made predominantly of nitrogen (as it still is), carbon dioxide, carbon monoxide, water vapour and very little oxygen. This is said to a mildly reducing atmosphere. Sometime between 3,500,000,000 and 4,000,000,000 bacteria evolved that could using light to drive their life processes… photosynthesis evolved… oxygen is a by-product of converting carbon dioxide and water into sugar. As photosynthetic life spread, more and more oxygen was made and our atmosphere change to what it is today… one that is oxidising. Basically, even today we live on the farts of bacteria and plants!