REHS Exam Questions and Answers (2026) |
Complete Breakdown with Verified Answers |
A+ Verified
The presence of which of the following is most easily identified by laboratory analysis in
water contaminated by feces?
a. shigella dysenteriae
b. coliform
c. entamoeba histolytica
d. salmonella typhosa -✓✓coliform
Which of the following disinfecting compounds can be used in full strength for
disinfecting?
a. perchloron
b. calcium hypochlorite
c. chlorinated lime
d. sodium hypochlorite -✓✓sodium hypochlorite
This substance is the first product of the decomposition of organic matter. its presence
in water usually indicates "fresh pollution" of sanitary significance. what is it?
a. ammonia
b. sugar
c. carbon dioxide
d. hydrogen sulfide -✓✓ammonia
The presence of which of the following elements in water treatment plant effluent is
used as a measure of filtration efficiency?
a. copper
b. aluminum
c. zinc
d. lead -✓✓aluminum
Which of the following is not used to disinfect water?
a. chlorine
b. bromine
c. fluorine
d. iodine -✓✓fluorine
,The presence of which of the following in water would indicate past of possibly
intermittent pollution?
a. streptococcus fecalis
b. escherichia coli
c. clostridium perfringens
d. enterococci -✓✓clostridium perfringens
Often over 90% of sodium arsenate can be removed by
a. filtration
b. coagulation
c. ion exchange
d. all of the above -✓✓coagulation
Reduction of the level of fluorides in drinking water can be accomplished by
a. coagulation
b. lime softening
c. ion exchange
d. all of the above -✓✓all of the above
When collecting bacteriological samples that have been chlorinated, what chemical is
used to chlorinate the water?
a. sodium sulfate
b. sodium thiosulfate
c. sodium bisulfate
d. sodium bisulfite -✓✓sodium thiosulfate
Methylene blue active substance (MBAS) is a test to identify
a. hardness of water
b. iron in water
c. presence of detergents containing phosphates
d. presence of coliform in bacteria -✓✓presence of detergents containing phosphates
Which organism is not known as an iron bacterium?
a. crenothrix
b. giardia lamblia
c. ferric chloride
d. leptothrix -✓✓giardia lamblia
The final product in biochemical oxidation of ammonia yields;
,a. nitride
b. nitrite
c. nitrate
d. nitrogen -✓✓nitrate
Which contaminant in water is associated with methemoglobinemia?
a. zinc
b. lead
c. copper
d. nitrate -✓✓nitrate
The substance constantly used as a coagulant in water treatment is:
a. aluminum sulfate
b. calcium sulfate
c. potassium chloride
d. sodium phosphate -✓✓aluminum sulfate
The disinfecting ability of chlorine is affected most by:
a. BOD
b. temperature
c. hydrogen ion concentration
d. dissolved oxygen -✓✓hydrogen ion concentration
Alkalinity exists in three forms, which is not one of these forms?
a. bicarbonate
b. hydroxide
c. carbonate
d. hypochlorite -✓✓hypochlorite
Which of the following would not contribute to water hardness?
a. calcium sulfate
b. magnesium sulfate
c. calcium chloride
d. sodium chloride -✓✓sodium chloride
Improperly located wells, allowing fecal pollution of the water supply may lead to
outbreaks of:
a. botulism, leptospirosis, typhus fever, maria
b. brucellosis, strep infections, chlorea, yellow fever
c. salmonellosis, shigellosis, chlorea, hepatitis
, d. relapsing fever, histoplasmosis, psittacosis -✓✓salmonellosis, shigellosis, chlorea,
hepatitis
Historically in the US, most of the impetus for adequate water treatment came from the
need to control:
a. infectious hepatitis
b. tuberculosis
c. malaria
d. typhoid -✓✓typhoid
The liquid form of chlorine used for emergency disinfection of small volumes of
a. calcium hypochlorite
b. sodium hypochlorite
c. bromide hypochlorite
d. potassium hypochlorite -✓✓sodium hypochlorite
The presumptive evidence of the presence of coliform in the MPN test is:
a. the color change in the culture media
b. turbidity of the culture broth
c. the presence of gas from the fermentation of the media
d. metallic sheen of colonies -✓✓the presence of gas from the fermentation of the
media
If hard water is softened by the ion exchange method, which one of the following will
increase?
a. dissolved oxygen
b. iron
c. p1-1
d. sodium -✓✓sodium
The langelier index is used to determine the point of stability of
a. aluminum sulfate
b. calcium carbonate
c. water pH
d. HOCL -✓✓calcium carbonate
The manner in which water moves from place to place, changing from one form to
another is called the:
a. evaporation cycle
b. hydrologic cycle
Complete Breakdown with Verified Answers |
A+ Verified
The presence of which of the following is most easily identified by laboratory analysis in
water contaminated by feces?
a. shigella dysenteriae
b. coliform
c. entamoeba histolytica
d. salmonella typhosa -✓✓coliform
Which of the following disinfecting compounds can be used in full strength for
disinfecting?
a. perchloron
b. calcium hypochlorite
c. chlorinated lime
d. sodium hypochlorite -✓✓sodium hypochlorite
This substance is the first product of the decomposition of organic matter. its presence
in water usually indicates "fresh pollution" of sanitary significance. what is it?
a. ammonia
b. sugar
c. carbon dioxide
d. hydrogen sulfide -✓✓ammonia
The presence of which of the following elements in water treatment plant effluent is
used as a measure of filtration efficiency?
a. copper
b. aluminum
c. zinc
d. lead -✓✓aluminum
Which of the following is not used to disinfect water?
a. chlorine
b. bromine
c. fluorine
d. iodine -✓✓fluorine
,The presence of which of the following in water would indicate past of possibly
intermittent pollution?
a. streptococcus fecalis
b. escherichia coli
c. clostridium perfringens
d. enterococci -✓✓clostridium perfringens
Often over 90% of sodium arsenate can be removed by
a. filtration
b. coagulation
c. ion exchange
d. all of the above -✓✓coagulation
Reduction of the level of fluorides in drinking water can be accomplished by
a. coagulation
b. lime softening
c. ion exchange
d. all of the above -✓✓all of the above
When collecting bacteriological samples that have been chlorinated, what chemical is
used to chlorinate the water?
a. sodium sulfate
b. sodium thiosulfate
c. sodium bisulfate
d. sodium bisulfite -✓✓sodium thiosulfate
Methylene blue active substance (MBAS) is a test to identify
a. hardness of water
b. iron in water
c. presence of detergents containing phosphates
d. presence of coliform in bacteria -✓✓presence of detergents containing phosphates
Which organism is not known as an iron bacterium?
a. crenothrix
b. giardia lamblia
c. ferric chloride
d. leptothrix -✓✓giardia lamblia
The final product in biochemical oxidation of ammonia yields;
,a. nitride
b. nitrite
c. nitrate
d. nitrogen -✓✓nitrate
Which contaminant in water is associated with methemoglobinemia?
a. zinc
b. lead
c. copper
d. nitrate -✓✓nitrate
The substance constantly used as a coagulant in water treatment is:
a. aluminum sulfate
b. calcium sulfate
c. potassium chloride
d. sodium phosphate -✓✓aluminum sulfate
The disinfecting ability of chlorine is affected most by:
a. BOD
b. temperature
c. hydrogen ion concentration
d. dissolved oxygen -✓✓hydrogen ion concentration
Alkalinity exists in three forms, which is not one of these forms?
a. bicarbonate
b. hydroxide
c. carbonate
d. hypochlorite -✓✓hypochlorite
Which of the following would not contribute to water hardness?
a. calcium sulfate
b. magnesium sulfate
c. calcium chloride
d. sodium chloride -✓✓sodium chloride
Improperly located wells, allowing fecal pollution of the water supply may lead to
outbreaks of:
a. botulism, leptospirosis, typhus fever, maria
b. brucellosis, strep infections, chlorea, yellow fever
c. salmonellosis, shigellosis, chlorea, hepatitis
, d. relapsing fever, histoplasmosis, psittacosis -✓✓salmonellosis, shigellosis, chlorea,
hepatitis
Historically in the US, most of the impetus for adequate water treatment came from the
need to control:
a. infectious hepatitis
b. tuberculosis
c. malaria
d. typhoid -✓✓typhoid
The liquid form of chlorine used for emergency disinfection of small volumes of
a. calcium hypochlorite
b. sodium hypochlorite
c. bromide hypochlorite
d. potassium hypochlorite -✓✓sodium hypochlorite
The presumptive evidence of the presence of coliform in the MPN test is:
a. the color change in the culture media
b. turbidity of the culture broth
c. the presence of gas from the fermentation of the media
d. metallic sheen of colonies -✓✓the presence of gas from the fermentation of the
media
If hard water is softened by the ion exchange method, which one of the following will
increase?
a. dissolved oxygen
b. iron
c. p1-1
d. sodium -✓✓sodium
The langelier index is used to determine the point of stability of
a. aluminum sulfate
b. calcium carbonate
c. water pH
d. HOCL -✓✓calcium carbonate
The manner in which water moves from place to place, changing from one form to
another is called the:
a. evaporation cycle
b. hydrologic cycle
