A colorless, odorless, tasteless, inert, and non-explosive gas, N2, that is relatively inactive chemically; it occupies about 3/4 (by volume) of dry air. Its importance lies chiefly in its compounds, which include nitrous oxide, nitric acid, ammonia, fertilizers, proteins, etc. Tank sizes available: 20, 40, 80, 113, and 225 cubic feet. Atomic symbol N, atomic number 7.Also see acetylene, argon, carbon dioxide, helium, hydrogen, and oxygen.