| Answer | Crossword Clue |
|---|---|
| ALKALIS | They have high pHs |
| ACIDS | They have low pH's |
| ACIDS | They have pH's of less than 7 |
| TOPHATS | They have high crowns |
| ASPIRERS | They have high hopes |
| ELS | They have high stations |
| BUMPERCARS | They have a high collision rate |
| BLACKHOLES | They have extremely high gravitational fields |
