Across
- 1. Smallest unit of matter
- 4. Object that attracts iron or steel
- 5. Force that pulls objects toward the Earth
- 7. Electromagnetic wave visible to the human eye
- 9. Needed to do work; can’t be created or destroyed
- 12. Erupts with lava and ash
- 13. Process plants use to make food from sunlight
- 16. Object that orbits a planet; can be natural or artificial
- 17. Carries genetic information
- 19. Trait that helps a species survive in its environment
Down
- 2. Mass times velocity; conserved in collisions
- 3. Related to the Sun
- 6. Electric potential difference
- 8. To process waste into reusable material
- 10. Single-celled organisms, some helpful, some harmful
- 11. A scientific test or procedure
- 14. A cloud of gas and dust in space
- 15. Negatively charged particle orbiting the nucleus
- 18. A person trained to travel in space