Atmosphere around us consists of mixture gases, mainly gas is Oxygen and Nitrogen, also contains of smaller amount of Water Vapor, Argon, Carbon Dioxide and rare gases

Composition Symbol Volume Temperature Degree
Nitrogen N2 78.084 % -196°C
Oxygen O2 20.947 % -183°C
Argon Ar 0.934 % -186°C
Carbon Dioxide CO2 0.033 % -78°C
Neon Ne 18.20 PPM 246°C
Helium He 5.20 PPM -269°C
Krypton Kr 1.10 PPM -152°C
Sulfur Dioxide SO2 1.00 PPM -10°C
Methane CH4 2.00 PPM -161.5°C
Hydrogen H2 0.50 PPM -253°C
Nitrous Oxide N2O 0.50 PPM -88°C
Xenon Xe 0.09 PPM -108°C
Ozone O3 0.07 PPM 40°C
Nitrous Dioxide NO2 0.02 PPM 38.5°C
Iodine L2 0.01 PPM 184.3°C
Water Vapor H2O 4.0 PPM 100°C
Carbon Monoxide CO Trace -192°C
Ammonia NH3 Trace -35.5°C
Composition Volume Contaminates
Nitrogen 99.5 % Argon + Oxygen
Oxygen 99.999 % Nitrogen + Water + Argon
Argon 99.999 % Nitrogen + Oxygen + Water + Acetylene
Carbon Dioxide 99.98 % Trace of Air + Hydrocarbon
Hydrogen 99.5 % Oxygen
Acetylene 99.999 % Trace of Air [ Low Level NH3 ]

Liquefied Gas ...
Gases which can become liquids at normal temperatures when they are inside cylinders under pressure, they exist inside the cylinder in a liquid vapor balance or equilibrium, initially the cylinder is almost full of liquid and gas fills the space above the liquid, as gas is removed from the cylinder, enough liquid evaporates to replace it, keeping the pressure in the cylinder constant such as Ammonia, Propane, Nitrous Oxide and Carbon Dioxide
Non-liquefied Gas ...
These gases do not become liquid when they are compressed at normal temperatures, even at very high pressures such as Oxygen, Nitrogen, Helium and Argon.
Dissolved Gas ...
Acetylene is the only common dissolved gas, unstable chemically and can explode even at atmospheric pressure.
Flammable Gas ...
This can burn or explode under certain conditions and concentration of gas in air or contact with oxidizing gas or ignition source such as Acetylene, Hydrogen, Butane and Propane
Oxidizing Gas ...
Any gas include Oxygen higher than atmospheric concentrations above 23% : 25% can react rapidly and violently with combustible material such as Nitrous Oxide