1,nature:  is tasteless odorless, not combustion, or combustion under normal circumstances ,, is an inert gas.

 2,usless: It is for low-temperature superconducting technology and the cold source. Can also be used as high vacuum devices, atomic reactors, such as the spacecraft leak detection agents and magnesium, zirconium, aluminum, titanium and other metal welding the protection of gas. GC also be used for the analysis of the carrier gas, the balloon inflated, with the protection of arc welding gas, mixed gas diving with the thermometer and gas-filled..