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The noble gases group The noble gases are a group of non-metal elements in a gaseous state , which are almost totally chemically inert . They therefore occur in nature as individual atoms , and not as compounds . Enrichment Colorful tubes in advertising billboards Advertising billboards often use colorful lighting tubes bent into various shapes , which are commonly known as “ neon lights” . These tubes light up when an electric current is sent through a gas that fills the tube . When an electric current passes through the gas , it emits light in a typical color . When the tube is filled with neon gas , the light emitted is red . To achieve lighting in a variety of colors , the tubes are filled with different gases or with a blend of gases . Times Square by night , New York , 2008

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