Liquid Helium

At standard pressure, the chemical element helium exists in a liquid form only at the extremely low temperature of −269 °C. Its boiling point. The density of liquid helium-4 at its boiling point and a pressure of one atmosphere (101.3 kilopascals) is about 0.125 grams per cm3, or about 1/8th the density of liquid water.

The major use in superconducting magnets such as those used in magnetic resonance imaging (MRI), nuclear magnetic resonance (NMR), Magneto encephalography (MEG), and experiments in physics, such as low temperature Mossbauer spectroscopy.

Gaseous helium is used as a coolant during the drawing of optical fibers, as a carrier gas for chromatography, and as a leak detection gas in a variety of industries. Being both lighter than air and nonflammable, helium is used to inflate balloons and airships.