Assertion: noble gas | /r/HasProperty | most helium
Facets:
value: most often
type: DEGREE
Source sentences:
text: The noble gases—most often helium and argon, the least expensive—are used to provide chemically unreactive environments for such operations as cutting, welding, and refining of metals such as aluminum (atmospheric oxygen and, in some cases, nitrogen or carbon dioxide would react with the hot metal).