Across
- 2. Gas humans breathe in (6)
- 4. Opposite of acid (6)
- 6. Living things interacting with their environment (9)
- 8. Centre of an atom (6)
Down
- 1. Smallest part of an element (4)
- 3. Field pulling objects towards Earth (7
- 5. Process plants use to make food (14)
- 6. Change from liquid to gas (11)
- 7. Unit of force (6)