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REHS Exam Questions and Complete Answers

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REHS Exam Questions and Complete Answers

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Which of the following organisms are most resistant to unfavorable environmental conditions and
indicate past of possibly intermittent pollution?



a. fecal streptococci

b. eschericha coli

c. aerobacter aerogenes

d. clostridium sporulates - Answer: clostridium sporulates



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 - Answer: 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 - Answer: 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 - Answer: 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 - Answer: aluminum



Which of the following is not used to disinfect water?



a. chlorine

b. bromine

c. fluorine

d. iodine - Answer: 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 - Answer: clostridium perfringens



Often over 90% of sodium arsenate can be removed by



a. filtration

b. coagulation

c. ion exchange

d. all of the above - Answer: 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 - Answer: 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 - Answer: 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 - Answer: presence of detergents containing phosphates



Which organism is not known as an iron bacterium?



a. crenothrix

b. giardia lamblia

c. ferric chloride

d. leptothrix - Answer: giardia lamblia



The final product in biochemical oxidation of ammonia yields;



a. nitride

b. nitrite

, c. nitrate

d. nitrogen - Answer: nitrate



Which contaminant in water is associated with methemoglobinemia?



a. zinc

b. lead

c. copper

d. nitrate - Answer: nitrate



The substance constantly used as a coagulant in water treatment is:



a. aluminum sulfate

b. calcium sulfate

c. potassium chloride

d. sodium phosphate - Answer: aluminum sulfate



The disinfecting ability of chlorine is affected most by:



a. BOD

b. temperature

c. hydrogen ion concentration

d. dissolved oxygen - Answer: hydrogen ion concentration



Alkalinity exists in three forms, which is not one of these forms?



a. bicarbonate

b. hydroxide

c. carbonate

d. hypochlorite - Answer: hypochlorite

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