| Rating | Solver | Clue |
|---|---|---|
| HELIUM | Inert gas | |
| ARGON | Inert gas | |
| RADON | Inert gas | |
| XENON | Inert gas | |
| KRYPTON | Inert gas | |
| NEON | Inert Gas | |
| NITROGEN | ...orless, comprising four fifths of the atmosphere by volume. It is chemically very inert in the free state, and as such is incapable of supportin... | |
| PARAFFINE | ...sed as an illuminant and lubricant. It is very inert, not being acted upon by most of the strong chemical reagents. It was formerly regarded as ... | |