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CWEA LABORATORY ANALYST EXAM ALL GRADES 2025/2026
BANK | ACCURATE REAL EXAM VERSIONS | CURRENTLY
TESTING WITH A STUDY GUIDE AND KNOWLEDGE CHECK
FLASHCARDS | GUARANTEED PASS
What does COLOR measure? ......answer.....Amount of color units
(CU) in a sample. Color caused by natural metallic ions (Fe & Mg)
& industrial wastes.
What is the test summary for COLOR? ......answer.....Sample ->
Tubes -> Compare to color standards over light source
Which of the following techniques is used to isolate anionic
surfactants (as MBAS) from the sample matrix?
......answer.....Extraction
In the cyanide determination, which one of the following is not an
interference? ......answer.....Halogenated aromatics
Which of the following is not a major interference in phenol
determination? ......answer.....Hydroxy derivatives of benzene
A freshly prepared sodium hydroxide (NaOH) solution is
standardized against primary standard potassium acid phthalate
,2|Page
(KHC8H4O4). 0.8000 grams of potassium acid phthalate was
dissolved into 50 mL CO2-free water. 2-3 drops of phenolphthalein
were added. The sample was titrated to a faint pink endpoint with
22 mLs sodium hydroxide. What is the normality of the sodium
hydroxide? ......answer.....0.178 N
What does an ICP source consist of? ......answer.....A flowing stream
of argon gas ionized by an applied radio frequency
In gas chromatography, electron capture detectors (ECD) are used
to detect which of the following compounds?
......answer.....Chlorinated hydrocarbon pesticides
Why is methlyene chloride replaced by hexane in sample
preparation for analyses detected by GC electron capture detection
(ECD)? ......answer.....Chlorine compounds are detected by ECD
Which of the following methods is used to determine pesticides?
......answer.....EPA Method 608
What analysis uses the purge and trap technique?
......answer.....Volatile organic compound analysis
The test for inhibitory residues on glassware and plastic ware
determines the toxic or stimulatory effects of dishwashing
,3|Page
detergents used for bacterial analysis. Which bacterial genera is
used for this test? ......answer.....Enterobacter
The Water Suitability Test (Test for Bacteriological Quality of
Reagent Water) determines the toxic or stimulatory effects of the
distilled or deionized water system. Which bacteria genera is used
for this test? ......answer.....Enterobacter
Short-term toxicity tests are inappropriate for:
......answer.....determining chronic toxicity.
Basic requirements for toxicity tests do not include:
......answer.....documented re-use of control test organisms.
A test in which solutions and test organisms are placed in test
chambers and kept there for the duration of the test is called a:
......answer.....static test.
A test in which solution is replaced continuously in test chambers
through the test duration is called a: ......answer.....flow through
test.
A preliminary test designed to establish approximate toxicity of a
solution is called a: ......answer.....range finding test.
, 4|Page
A toxicity test designed to establish concentration at which a
particular end point occurs is called a: ......answer.....definitive test.
Which of the following types of control samples may be used to
determine accuracy? ......answer.....Certified reference material
Which of the following types of control samples may be used to
determine precision? ......answer.....Duplicate
The average flow in a treatment plant is 3.1 MGD. A chlorine
residual of 4.0 mg/L is maintained and the effluent must be
dechlorinated before discharging. If an excess of 0.5 mg/L of sulfur
dioxide is required after dechlorination, how many lbs/day of
sulfur dioxide must be added? ......answer.....106 lbs SO2/day
A plant serving a city of 50,000 population has an influent
settleable solids of 10 mL/L. If per capita contribution to the plant
flow is 100 gallons/day, how much sludge is produced in the plant
in cubic feet/day? ......answer.....6,684 cu ft/day
Which of the following formulas determines chlorine demand?
......answer.....Chlorine dose - chlorine residual = chlorine demand
What is the most important measurable parameter to judge the
performance of an anaerobic sludge digester? ......answer.....Volatile
solids reduction
CWEA LABORATORY ANALYST EXAM ALL GRADES 2025/2026
BANK | ACCURATE REAL EXAM VERSIONS | CURRENTLY
TESTING WITH A STUDY GUIDE AND KNOWLEDGE CHECK
FLASHCARDS | GUARANTEED PASS
What does COLOR measure? ......answer.....Amount of color units
(CU) in a sample. Color caused by natural metallic ions (Fe & Mg)
& industrial wastes.
What is the test summary for COLOR? ......answer.....Sample ->
Tubes -> Compare to color standards over light source
Which of the following techniques is used to isolate anionic
surfactants (as MBAS) from the sample matrix?
......answer.....Extraction
In the cyanide determination, which one of the following is not an
interference? ......answer.....Halogenated aromatics
Which of the following is not a major interference in phenol
determination? ......answer.....Hydroxy derivatives of benzene
A freshly prepared sodium hydroxide (NaOH) solution is
standardized against primary standard potassium acid phthalate
,2|Page
(KHC8H4O4). 0.8000 grams of potassium acid phthalate was
dissolved into 50 mL CO2-free water. 2-3 drops of phenolphthalein
were added. The sample was titrated to a faint pink endpoint with
22 mLs sodium hydroxide. What is the normality of the sodium
hydroxide? ......answer.....0.178 N
What does an ICP source consist of? ......answer.....A flowing stream
of argon gas ionized by an applied radio frequency
In gas chromatography, electron capture detectors (ECD) are used
to detect which of the following compounds?
......answer.....Chlorinated hydrocarbon pesticides
Why is methlyene chloride replaced by hexane in sample
preparation for analyses detected by GC electron capture detection
(ECD)? ......answer.....Chlorine compounds are detected by ECD
Which of the following methods is used to determine pesticides?
......answer.....EPA Method 608
What analysis uses the purge and trap technique?
......answer.....Volatile organic compound analysis
The test for inhibitory residues on glassware and plastic ware
determines the toxic or stimulatory effects of dishwashing
,3|Page
detergents used for bacterial analysis. Which bacterial genera is
used for this test? ......answer.....Enterobacter
The Water Suitability Test (Test for Bacteriological Quality of
Reagent Water) determines the toxic or stimulatory effects of the
distilled or deionized water system. Which bacteria genera is used
for this test? ......answer.....Enterobacter
Short-term toxicity tests are inappropriate for:
......answer.....determining chronic toxicity.
Basic requirements for toxicity tests do not include:
......answer.....documented re-use of control test organisms.
A test in which solutions and test organisms are placed in test
chambers and kept there for the duration of the test is called a:
......answer.....static test.
A test in which solution is replaced continuously in test chambers
through the test duration is called a: ......answer.....flow through
test.
A preliminary test designed to establish approximate toxicity of a
solution is called a: ......answer.....range finding test.
, 4|Page
A toxicity test designed to establish concentration at which a
particular end point occurs is called a: ......answer.....definitive test.
Which of the following types of control samples may be used to
determine accuracy? ......answer.....Certified reference material
Which of the following types of control samples may be used to
determine precision? ......answer.....Duplicate
The average flow in a treatment plant is 3.1 MGD. A chlorine
residual of 4.0 mg/L is maintained and the effluent must be
dechlorinated before discharging. If an excess of 0.5 mg/L of sulfur
dioxide is required after dechlorination, how many lbs/day of
sulfur dioxide must be added? ......answer.....106 lbs SO2/day
A plant serving a city of 50,000 population has an influent
settleable solids of 10 mL/L. If per capita contribution to the plant
flow is 100 gallons/day, how much sludge is produced in the plant
in cubic feet/day? ......answer.....6,684 cu ft/day
Which of the following formulas determines chlorine demand?
......answer.....Chlorine dose - chlorine residual = chlorine demand
What is the most important measurable parameter to judge the
performance of an anaerobic sludge digester? ......answer.....Volatile
solids reduction
