| Clue | Source | Date |
|---|---|---|
| Car exhaust gas, carbon ... | ||
| Oxide containing just one atom of oxygen in the molecule (8) | ||
| Carbon ____ | The Guardian Quick | 21 Nov 2023 |
| See 8 Down | The Telegraph Toughie | 26 Mar 2021 |
| Carbon ..., a poisonous gas | Irish Times Simplex | 16 Jul 2020 |
| Chemical process involving small number on team | ||
| Carbon --, deadly gas | The Telegraph General Knowledge | 17 Mar 2019 |