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REHS EXAM QUESTIONS AND CORRECT
DETAILED ANSWERS (VERIFIED ANSWERS)
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Which of the following organisms are most resistant to unfavorable environmental conditions and indicate past of possibly intermittent pollution?
- fecal streptococci
- eschericha coli
- aerobacter aerogenes
- clostridium sporulates
Correct answer: clostridium sporulates
The presence of which of the following is most easily identified by laboratory analysis in water contaminated by feces?
- shigella dysenteriae
- coliform
- entamoeba histolytica
- salmonella typhosa
Correct answer: coliform
Which of the following disinfecting compounds can be used in full strength for disinfecting?
- perchloron
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- calcium hypochlorite
- chlorinated lime
- sodium hypochlorite
Correct 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?
- ammonia
- sugar
- carbon dioxide
- hydrogen sulfide
Correct answer: ammonia
The presence of which of the following elements in water treatment plant effluent is used as a measure of filtration efficiency?
- copper
- aluminum
- zinc
- lead
Correct answer: aluminum
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Which of the following is not used to disinfect water?
- chlorine
- bromine
- fluorine
- iodine
Correct answer: fluorine
The presence of which of the following in water would indicate past of possibly intermittent pollution?
- streptococcus fecalis
- escherichia coli
- clostridium perfringens
- enterococci
Correct answer: clostridium perfringens
Often over 90% of sodium arsenate can be removed by
- filtration
- coagulation
- ion exchange
- all of the above
Correct answer: coagulation
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Reduction of the level of fluorides in drinking water can be accomplished by
- coagulation
- lime softening
- ion exchange
- all of the above
Correct answer: all of the above
When collecting bacteriological samples that have been chlorinated, what chemical is used to chlorinate the water?
- sodium sulfate
- sodium thiosulfate
- sodium bisulfate
- sodium bisulfite
Correct answer: sodium thiosulfate
Methylene blue active substance (MBAS) is a test to identify
- hardness of water
- iron in water
- presence of detergents containing phosphates
- presence of coliform in bacteria