What is the atomsphere composed up of (exact percentages)?

Answer 1

Good question. The air you breath is a collection of permanent gases such as Nitrogen, 78%, Oxygen, 21%, Argon, Neon Helium, Hydrogen, and Xenon together less than 1 % and variable gases such as water vapor (0-4%), Carbon dioxide (.04%) and other lesser gases and solid particles such as dust, soot, etc..

Answer 2

nitrogen (78 percent) and oxygen (21 percent). The atmospheric gases in the remaining 1 percent are argon (0.9 percent), carbon dioxide (0.03 percent), varying amounts of water vapor, and trace amounts of hydrogen, ozone, methane, carbon monoxide, helium, neon, krypton, and xenon.