Nitrogen
- Colourless, odourless, tasteless
- Usage: Ammonia manufacturing, Fertilizer industry, Refrigeration, cryo-preservation (Liquid Nitrogen), Nitric acid for explosives.
- Nitrogen constitutes 78 per cent of Earth’s atmosphere and is a constituent of all living tissues, as well as DNA.
- Nitrogen emission: Industrial processes, agriculture affluents.
- Nitrogen Oxide, a poisonous, reactive Nitrogen compound, is emitted by automobiles. It is also an indirect greenhouse gas, promoting photochemical reactions.

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