About N2Nitrogen,
with the chemical formula N2, is generally a colorless and odorless
gas, and generally, nitrogen is less dense than air. Nitrogen accounts
for 78.08% (volume fraction) of the total atmosphere and is one of the
main components of air. At standard atmospheric pressure, when nitrogen
is cooled to -195.8 ° C, it becomes a colorless liquid, and when cooled
to -209.8 ° C, liquid nitrogen becomes a snowy solid. Nitrogen is
chemically inert and difficult to react with other substances at room
temperature, so it is often used as a preservative. However, under high
temperature and high energy conditions, it can undergo chemical changes
with certain substances to prepare new substances useful to humans.