Drinking water

1. Name 5 substances that can contaminate  drinking water.

2. What makes the water ‘hard’?

3. Why is human habitation restricted in catchment areas surrounding dams and reservoirs?

4. For how long is water stored up in major reservoirs? Why?

5. Three chemicals that are added to the drinking water supply. Why are they added?

6. What is a colloid?

7. What are emulsions? Give examples.

8. Is butter an emulsion?

9. Paints and skin creams are emulsions. Right or wrong?

10. Describe the process of  flocculation.

11. What is the chemical used for flocculation ? What is its scientific name?

12. Write the different stages water from a river or lake goes through at a town water treatment plant to make drinking water.

Waste water

1.  What does sewage  washed down the drains in our home contain?

2. If we live in a big city, what happens to the sewage  from our home?

3. What is a septic tank? What happens in it?

4. What happens to the waste water at a sewage treatment plant?

5. Name some substances that should not be tipped down the kitchen sink. Why?

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