| Answer | Crossword Clue |
|---|---|
| LITHIA | Oxide of the lightest known metal. |
| lithium | a soft silver-white element of the alkali metal group that is the lightest metal known and that is used especially in alloys and glass, in chemical synthesis, and in storage batteries see element table |
| HYDROGEN | The lightest of all known substances. |
| METAL | Lithium is the lightest one known |
| strontian | an oxide of the metal strontium also STRONTIA |
| strontians | STRONTIAN, an oxide of the metal strontium also STRONTIA |
