From FDRâs brushes with death to Eleanorâs midnight ride with Amelia Earhart, here are 10 things you may not know about this presidential pair. 1. Franklin Roosevelt was related to 11 other presidents.
By volume, dry air contains 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.039% carbon dioxide, and small amounts of other gases. Air also contains a variable amount of water vapor, on average around 1% at sea level, and 0.4% over the entire atmosphere.y volume, dry air contains 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.039% carbon dioxide, and small amounts of other gases. Air also contains a variable amount of water vapor, on average around 1% at sea level, and 0.4% over the entire atmosphere.
Read this story at MIT News. Today, 21 percent of the air we breathe is made up of molecular oxygen. But this gas was not always in such ample, life-sustaining supply, and in fact was largely absent from the atmosphere for the first 2 billion years of Earthâs history. When, then, did oxygen first accumulate in the atmosphere?