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1. Softening is the process of removing:
   
   a. Iron and manganese b. Hydrogen sulfide c. Impurities d. Hardness
    

2. Hardness in water is mainly caused by the presence of___________.
   
   a. Lime and soda ash b. Arsenic c. Iron and manganese d. Calcium and magnesium
    

3. One method of softening public water supplies is _________.
   
   a. Chemical precipitation b. Iron removal filters c. Iron and manganese d. Pretreatment
    

4. Lime and soda ash are two chemicals used in ___________.
   
   a. Disinfection b. Sequestation c. Chemical precipitation d. Filtration
    

5. Flocculation is usually followed by _________.
   
   a. Chlorination b. Filtration c. Ionization d. Sedimentation
    

6. Minimum retention time in a flocculator is _________.
   
   a. 60 minutes b. 10 minutes c. 30 minutes d. 90 minutes
    

7. Detention time in a settling tank following flocculation is _________.
   
   a. 3-4 hours b. 1.5 - 3.0 hours c. minimum 15 minutes d. 4-5 hours
    

8. Proper lime doses are determined by using the __________.
   
   a. Softening test b. Magnesium test c. Bacteria test d. Jar test
    

9. Which chemical is used to increase alkalinity?
   
   a. Aluminum sulfate b. Chlorine gas c. Caustic solda d. Sulfuric acid
    

10. Which chemical is used to lower alkalinity?
    
    a. Hydrate lime b. Carbon dioxide c. Calcium hypochlorite d. Sodium aluminate
     

11. A water softening method used extensively in smaller water systems is:
    
    a. Filtration b. Oxidation c. Alkalinity removal d. Ion exchange
     

12. In ion exchange, calcium and magnesium ions are replaced by__________ ions.
    
    a. Nitrogen b. Sodium c. Hydrogen d. Carbon
     

13. Softener media most commonly used are called__________.
    
    a. Activated carbon b. Filter sand c. Gravel d. Synthetic zeolite
     

14. The compound used in ion exchange water softeners is called_________.
    
    a. Sodium chloride b. Ferric chloride c. Calcium hypochlorite d. Magnesium bicarbonate
     

15. Which test is not included in testing for water quality by an ion exchange softener?
    
    a. Total hardness of the raw and treated water b. Alkalinity c. Langelier index d. Chloride concentration in rinse water
    
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