Labels for oxygen gas must be what color?

• A. Green lettering on a white background
• B. Red lettering on a white background
• C. Black lettering on a yellow background
• D. Blue lettering on a white background

Answer: (A)

Color-coding on compressed-gas labels is meant to let you identify the gas at a glance. Oxygen gas uses green lettering on a white background because green is associated with oxygen/oxidizers in the standard labeling system, and the white background provides strong contrast for quick recognition. This helps prevent mixing up gases and guides safe handling since oxidizers support combustion but are not flammable themselves. Other gas labels use different color cues (for example, red commonly signals flammable gases, blue for health hazards, etc.), so green on white is the specific cue for oxygen.