Across
- 3. paper saturated with a chemical to show whether a substance is acidic or basic
- 7. a substance that speeds up chemical reactions without being used up in a reaction
- 11. a chemical used to control weeds
- 12. a mineral which the body needs 100mg/day
- 13. the combining of an acid compound having a pH value of less than 7
- 19. a chemical used to control pests
- 21. the process of adding calcium carbonate to the environment
Down
- 1. a chemical that produces a basic substance having a pH value of more than 7
- 2. a chemical used to control moulds and fungi
- 4. rain or snow containing acid compounds from the air
- 5. an organic nutrient made of carbon, hydrogen and oxygen
- 6. a scale the measures the acidity or alkalinity of a substance
- 8. the sate of matter which has no definite shape
- 9. how much calcium do we need every day
- 10. a mineral that the body requires at lest 100mg/day in order to maintain health
- 14. a chemical used to control insects
- 15. the process whereby chemicals accumulate in the tissue of organisms along the food chain.
- 16. a chemical that produces an acidic substance, having a pH value of less than 7
- 17. a chemical that changes colour to indicate whether a substance is an acid or a base
- 18. a mixture of a plant compounds used as a chemical indicator
- 20. a special molecule that regulates chemical reactions in living organisms