Chemistry of Gases and Applications

Main constituent in air is nitrogen.
The proportion of nitrogen in the open air is 78% by volume.
Note:
Air is a mixture of gases. The volume percent of nitrogen and oxygen are 78%and 21% respectively. Air also contains tiny amounts of carbon dioxide, argon, methane, ozone and water vapour.

Argon is used in light bulbs. The very thin metal filament inside the bulb would react with oxygen and burn away if the bulb were filled with air instead of argon. Argon stops the filament burning away because it is unreactive.

A mixture of nitrogen and carbon dioxide can be distinguished by passing it through lime water. Because nitrogen does not turn lime water milky and carbon dioxide forms carbonate with lime which makes lime water milky. From this we can conclude that nitrogen gas does not react with lime water, hence, it is most useful in removing nitrogen from air.

$ N{ H } _{ 4 }{ NO } _{ 2 }\xrightarrow [ thermal\quad decomposition ]{ \Delta  } { N } _{ 2 }+2{ H } _{ 2 }O $

Inert gases are also known as zero-valent gases, zero group elements or noble gases. They have completely filled valence shell and are chemically unreactive.

At low temperatures nitrogen can be liquefied on compression.

Nitrogen gas is neutral to litmus and is a non combustible nor supports combustion and can be liquefied on compression at low temperatures. It is non poisonous.

Nitrogen is not a supporter of COMBUSTION.
Nitrogen is a colorless, odorless, tasteless diatomic gas. It is found in Group 15 of the periodic table. It does not burn, does not support combustion, and is only slightly soluble in water. It is relatively inactive chemically, but many of its compounds display marked reactivity.

Nitrogen is a non supporter of combustion.
Nitrogen is a colorless, odorless, tasteless diatomic gas. It is found in Group 15 of the periodic table. It does not burn, does not support combustion.

Air has fixed composition with less oxygen at high altitudes. Air contains 78% nitrogen and 21% oxygen and less than 1% He, Ar, Ne and water vapor content. This composition remains fixed at all locations but the oxygen becomes less dense at high altitudes so it is difficult to breathe in such low concentration of air.

By volume dry air contains $78.09\%$ Nitrogen, $20.95\%$ Oxygen, $0.93\%$ Argon, $0.04\%$ Carbon dioxide and small traces of other gases.

By volume dry air contains $78.09\%$ Nitrogen, $20.95\%$ Oxygen, $0.93\%$ Argon, $0.04\%$ Carbon dioxide and small traces of other gases.

The percentage of Nitrogen in air is $78\%$.

Air contains 78% Nitrogen. So, it contributes more no. of moles to partial pressure than any other gas in the atmosphere. So, it has the highest partial pressure. 

The most abundant gas in the Earth's atmosphere is nitrogen, which accounts for about 78% of the mass of dry air.