Liquid helium is used cryogenics, cooling of super-conducting magnets.
Is the second least reactive noble gas, after neon, and thus the second least reactive of all elements.
Helium is the least water soluble monatomic gas, and one of the least water soluble of any gas.
Solid helium requires a temperature of 1-1.5K (about 273°C or -457°F) and about 25 bar (2.5 MPa) of pressure.
The thermal conductivity of Helium II is greater than that of any other known substance, a million times that of Helium I and several hundred times that of Copper.
Helium IV is produced by alpha decay of heavier radioactive elements.
Liquid helium - 4 can be cooled to about 1 kelvin using evaporative cooling in a 1-k pot.
Helium – 3&4 are the stable isotopes.
Helium is extracted by fractional distillation from natural gas, which can contain up to 7% helium.
