- - Xenon or krypton
- - Krypton or xenon
- - Xenon, e.g
- - 21-Across, e.g.
- - Krypton, e.g
- - 37-Across, e.g.
- - Krypton, for one
- - Neon, e.g
- - ir doesn't react very well
- - noble air?
- - Element such as helium, neon etc
- - Relatively piquant
- - 'Noble' thing
- - Noble at the end of a table?
- - Noble one
- - Noble element
- - One highly unlikely to react
- - Erstwhile name for a "noble" element
- - Last-column element on the periodic table
- - It doesn't react very well
- - Neon or argon
- - Argon or xenon, say
- - Element on the far-right side of the periodic table
- - Helium, for one
- - Neon, for one
- - Xenon, for one
- - Argon or xenon
- - 49-Down, for example
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- [ Other definitions ]