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

2. Chlorine has ___________ uses.
a) diverse
b) limited

3. Chlorine compounds in water form _____.
a) sodium hypochlorite
b) calcium hypochlorite
c) hypochlorous acid
d) hypochlorite ion

4. ________ is a stronger oxidant and has greater biocide efficacy.
a) Hypochlorous acid (HOCl) b) Hypochlorite ion (OCl)

5. Reactions with ammonia to form chloramines can be overcome by __________.
a) chlorine gas
b) high test chlorine
c) breakpoint chlorination

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