| 100% | ETHANE | 6 | Natural-gas compound with the formula C2H6 |
| 61% | LYE | 3 | Chemical compound with the formula NaOH |
| 48% | IRAN | 4 | Nation with the most natural-gas reserves |
| 47% | CERIA | 5 | Short name for the compound with the formula CeO2, used by glassmaking hobbyists for polishing |
| 46% | NITRATE | 7 | Ion with the formula N3- |
| 46% | ETHENE | 6 | Hydrocarbon with the formula C2H4 |
| 45% | HYDROXYL | 8 | Chemical group with the formula -OH |
| 44% | ISOMER | 6 | Compound with the same atoms in a different arrangement |
| 43% | ISOMER | 6 | Compound with the same number of atoms in a different arrangement |
| 42% | TNT | 3 | Explosive with the chemical formula C7H5N3O6 |
| 41% | OXYGEN | 6 | Gas with the symbol O |
| 40% | ISOMER | 6 | Molecule with the same chemical formula as another |
| 40% | ETHANE | 6 | Compound in natural gas |
| 40% | ESSO | 4 | Gas brand with the slogan "Put a tiger in your tank" |
| 40% | ISOMERS | 7 | Molecules with the same chemical formula but different structures |
| 39% | LIQUIDS | 7 | The third component with gases and solids |
| 39% | ROUGE | 5 | What ancient Romans made with the toxic compound red lead |
| 39% | ISSARAE | 7 | "Insecure" actress with the beauty brand Sienna Naturals: 2 wds. |
| 39% | SASK | 4 | The only Canadian prov. with no natural borders |
| 38% | PLASMATVS | 9 | Screens with gas in the glass |
| 38% | OPEC | 4 | Grp. with clout at the gas pump |
| 37% | TIMEHEALS | 9 | With 12 Across, maxim stressing the natural resolution of problems |
| 37% | ARGON | 5 | Noble gas with the symbol Ar |
| 37% | XENON | 5 | Noble gas with the symbol Xe |
| 36% | RADON | 5 | Hazardous gas with the periodic symbol Rn |
| 36% | EASE | 4 | Let off the gas, with "up" |
| 35% | REV | 3 | Step on the gas, rhymes with "Bev" |
| 34% | THIOL | 5 | Compound added to natural gas to give it an odor |
| 34% | NITRO | 5 | Prefix with "gen" that is the most abundant gas in our atmosphere |
| 34% | KEITHMOON | 9 | The Who drummer who shares his name with Earth's only natural satellite (2 wds.) |