Historical clue formulations

• Krypton and xenon — 2026-04-06
• Rightmost column on the periodic table — 2025-07-04
• Sublimation products — 2025-01-25
• What Boyle's law pertains to — 2024-12-29
• Elements that make up the atmosphere — 2022-05-16
• Six of the first 10 elements on the periodic table — 2021-07-14
• Oxygen and nitrogen — 2018-12-03
• Argon and xenon — 2016-07-11
• Rightmost column of the periodic table, e.g. — 2016-01-23
• Krypton and others — 2010-04-07
• Exhausts, say — 2006-10-20
• Atmospheric mix — 2006-07-13
• Some cause laughter — 2006-03-11
• Terrific times, slangily — 2005-12-15
• Xenon and neon — 2005-12-12
• Some are inert — 2003-07-23
• Some are inert — 2001-12-18
• Subject of Avogadro's law — 2001-10-14
• Krypton and xenon — 1998-03-08
• Volcanic elements — 1997-04-10
• Fuels (up) — 1996-05-07
• Firedamps — 1994-02-18