Can you rank (highest to lowest) these elements, when not combined in a molecule, in the order of their average abundance in the atmosphere of the earth?
Answer is: Nitrogen - Oxygen - Helium - Hydrogen
The most abundant element is Nitrogen at about 78%.
Next is Oxygen at 21%.
Next would be Helium at about only .0054%.
Finally Hydrogen is only 0.00055%.
More Info:
nssdc.gsfc.nasa.gov