Related Clues:

• Element number 54
• Gaseous element
• Flash lamp filler
• Colorless gas
• Element #54
• A noble gas
• Chemical element
• Gas used in high-intensity headlights
• Gas used in tubes
• Flashbulb element
• It's 54, periodically speaking
• Rare gas
• It's under krypton on the periodic table
• Arc-lamp gas
• Gas in arc lamps