CERTIFICATION ACTION LINE
By Joseph Harrison CWS-VI, P.E., Technical Director Water Quality Association, Lisle, IL
Questions about chlorine
Answers to these questions appear on page 46. Certification Action Line features questions and answers typical of those appearing in Water Quality Association (WQA) certification examinations. Some answers may not satisfy everyone or every condition.
1. Chlorine is a member of the ______ family.
a) alkali
b) alkaline earth
c) halogen
d) actinide
3. Chlorine compounds in water form _____.
a) sodium hypochlorite
b) calcium hypochlorite
c) hypochlorous acid
d) hypochlorite ion
5. Reactions with ammonia to form chloramines can be overcome by __________.
a) chlorine gas
b) high test chlorine
c) breakpoint chlorination
2. Chlorine has ___________ uses.
a) diverse
b) limited
4. ________ is a stronger oxidant and has
greater biocide efficacy.
a) Hypochlorous acid (HOCl)
b) Hypochlorite ion (OCl-)
6. Chlorine demand can be increased by
___________ in water.
a) ferrous iron (Fe++)
b) manganese (Mn++)
c) sulfides (S=)
d) humic organic substances
e) pollen
f) all of the above
7. Compared to chlorine, chlorine dioxide
(ClO2) is a ______________ powerful
water disinfectant.
a) more
b) less
8. Chlorine dioxide is purchased from a supply
house in the form of sodium chlorite (NaClO2).
a) True
b) False
9. The treatment of natural waters with chlorine dioxide results in these by-product
formations.
a) chloroform and other trihalomethanes
b) chlorite ion (ClO2-)
c) chloramines
d) chlorate ion (ClO3-)
10. High pH _____________ the effectiveness of chlorine dioxide disinfection and
oxidation in water.
a) increases
b) decreases
c) does not affect
