ChemCom Quiz
Chapter 1D/E Water Purification

1) Water can be purified thru different natural processes. Which one of these processes does not help purify water
a) evaporation b) photosynthesis c) bacterial action d) filtration

2) Hard water can contain all of the following ions except
a) calcium b) sodium c) magnesium d) iron

3) When a hard water ion bonds to a soap molecule
a) the soap dissolves and wont clean
b) the soap doesn't dissolve wont clean
c) the soap dissolves and forms suds
d) the soap doesn't dissolve and does form suds

4) What is needed to form scale in a pot or on the inside of a water pipe?
a) hard water b) HCO₃ion(bicarbonate) c) hot water d) all of these

5) Which if these softens water by reacting with the hardness ion and forming a cloudy precipitate
a) washing soda, Na₂CO₃ b) Calgon c) ion exchange resin
d) all of these e) none of these

6) This method of water softening removes hardness ions and replaces them with sodium ions which does not effect the soap
a) washing soda, Na₂CO₃ b) Calgon c) ion exchange resin
d) all of these e) none of these

7) When detergent is placed in hard water the hardness ion combine with the detergent molecules and
a) weaken detergents cleaning power by forming a soluble substance
b) weaken detergents cleaning power by forming a insoluble substance
c) does not weaken the detergents cleaning power
d) makes it more difficult to rinse the detergent from the clothes

8) Look at the picture of the water softener. At what 2 points would hard water be found
a) 1 and 2 b) 2 and 3 c) 3 and 4 d) 1 and 3 e) 1 and 4

9) When the ion exchange resin in a water softener is regenerated it
a) gains hardness ions b) losses hardness ions c) gains sodium ions
d) both a and c e) both b and c

10) Bacterial action purifies water in lakes streams and oceans and
a) on the surface of the ground b) in the first couple of inches of soil
c) deep underground d) in the air

11) Bacterial action removes ______________ from water
a) suspended solids b) dissolved salts c) dissolved organic matter
d) colloidal clay particles

12) Bacterial action adds ___________ to the water it purifies
a) suspended solids b) oxygen c) carbon dioxide(acid) d) hardness ions

13) Ground water is impure and contains hardness ions. At what point has the water gained these ions
a) when the water evaporated from the surface of the earth to form clouds
b) as the water fell thru the sky as rain
c) as bacteria purified the water
d) as the water filtered thru the rocks underground
e) all of these

14) There are 5 steps in the treatment of sewage. Pick the list that's in the correct order
a) screening and sand removal, primary settling, aeration, secondary settling, chlorination and discharge
b) primary settling,screening and sand removal,secondary settling, aeration, chlorination and discharge
c) primary settling, aeration, screening and sand removal,secondary settling, chlorination and discharge
d) chlorination, primary settling, screening and sand removal,aeration, secondary settling and discharge
e)aeration, screening and sand removal, primary settling,chlorination, secondary settling and discharge

15) At what stage in the treatment do bacteria consume dissolve substances in the sewage
a)primary settling b) secondary settling c) screening and sand removal d) aeration e) chlorination

16) Soap is added to 3 water sample X, Y, Z
Na₂CO₃ s added to 3 other samples of the same water .

The softest water is a) sample x b) sample y c) sample z
d) both sample x and z

17) The purpose of adding chlorine to water is to
a) reduce the pH b) remove impurities c) kill bacteria d) all of these

18) THM, trihalomethanes are formed when chlorine reacts with ___________in water
a) hardness ions b) suspended matter c) bacteria d) organic chemicals from decayed matter

19) THM are not allowed in water at levels above 100 ppb because
a) they interfere with soap b) cause scale to form in pipes
c) cause cancer d) cause gas bubble disease in fish

20) THM can be removed from water by
a) sand filtration b) flocculation c) chlorination d) charcoal filtration

21) Combined sewer systems send ______________to sewage treatment facilities
a) home sewage b) rainwater c) groundwater d) both a and b
e) a,b and c

22) Which problem does the Deep Tunnel project solve
a) it helps reduce the amount of sewage that is produced
b) it stores sewage for later treatment that would normally be released in the lake
c) it eliminates all combined sewer systems that were built in the last 100 years
d) it provides a place for bacteria to begin to consume the waste in sewage

23) What is the purpose of flocculation in water treatment
a) removes dissolve substances
b) kills bacteria
c) removes colloidal clay
d) removes odor from water
e) all of these

24) If a combined sewer system was totally replaced by a separate sewer system, which of following would happen?
a) less water would be treated at the sewage treatment plant
b) communities would require less drinking water
c) rainwater would be purified at sewage treatment plants
d) there would be less need to treat sewage from the home

Fill in a for true and b for false

25) As evaporates it becomes more pure T F

26) The process of evaporation and condensation can add hardness to water
T F

27) Scale is a precipitate of hard water which coats containers of hot water T F

28) In water treatment water is filtered right after its flocculated T F

29) At the end of water treatment water is chlorinated to protect it in the pipes T F

30) Nature can often purify some polluted water T F





Essay Name _______________________________
Chapter 1D
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1) Below is a picture of a water treatment plant. List these terms next to
the matching step of the treatment process
Flocculation, sand filtration, post-chlorination, pre-chlorination, settling, screening

For each step explain how it works in 1 sentence and explain what is removed
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2) The Riverwood Town Council has just decided how to solve the problem of the fish kill. Write a "Letter to the Editor" of the Riverwood Gazette expressing your point of view on the decision
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Analyze your opinion. Explain what values are being expressed in your point of view

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