1) Helium (symbol He) is a colorless, odorless, tasteless chemical element, one of the nearly inert noble gases of the periodic table of elements. Its boiling and melting points are the lowest among the elements; except in extreme conditions, it exists only as a gas. At extremely low temperatures, it is a superfluid, a nearly frictionless phase of matter with unusual properties.
Helium is the second most abundant element in the universe, created from nuclear fusion in stars. On Earth, helium is primarily a product of radioactive decay and is found in significant amounts only in natural gas. It is used in cryogenics, in deep-sea breathing systems, for inflating balloons and airships, and as a protective gas for many industrial purposes, such as arc welding.source: From Wikipedia, the free encyclopedia