1SDS 1-9,18-22

1.

2.

A.Evaporation of water vapor: removes nearly all dissolved substances.

B. Bacterial action: changes dissolved substances into simple compounds. 

C. Filtration through sand and gravel: removes nearly all unwanted matter.

3. They both remove suspended particles in the water.

4. They calcium oxides basic property neutralizes the acidity of the water.

5. Sometimes 1ppm of fluoride is used due to the risk of tooth decay.

6. Chlorinated water is far healthier due to the fact that it has helped prevent from waterborne diseases.

7. Chlorine in water can react with organic compounds made by decomposing animal and plant water to form substances that can be harmful to humans.

8. Water from a clear mountain stream may require chlorination to make it safe for drinking due to various types of bacterias found on the ground or other harmful substances that the water may have picked up on the way down the mountain.

9. Charcoal filters: they remove most organic compounds from water. or Sand Filtration, which  removes nearly all unwanted matter.

18. Due to evaporation being the first step of the hydrological cycle, none of the following steps could happen because evaporation is the starting point.

19. Water evaporates as vapor (Gas), forms into water droplets in clouds (liquid), and falls as either rain water (liquid), snow, or hail (solids). 

20. The EPA is recognizing the difficulties of using alternatives and accepts the foreign substances in extremely low concentrations. 

21. 

22. 

a. 1 ppm fluoride.

b. 7 ppm fluoride.c. 365 ppm fluoride.