CA-NV AWWA Water Quality Laboratory Analysts Grade 2 Practice Exam - 100 Questions
LATEST WITH CORRECT ANSWERS
**QUESTION 1:**
According to the Safe Drinking Water Act (SDWA), what is the Maximum Contaminant Level
Goal (MCLG) defined as?
A) The enforceable limit set as close to the MCLG as feasible
B) The maximum permissible level of a contaminant in water delivered to any user of a
public water system
C) The level of a contaminant in drinking water below which there is no known or expected
risk to health
D) The highest concentration of a contaminant that is allowed in drinking water
**ANSWER:** C
**EXPLANATION:** The MCLG is a non-enforceable health-based goal set at a level where
no known or anticipated adverse health effects occur, allowing for an adequate margin of
safety.
**QUESTION 2:**
In a drinking water laboratory, which class of chemical requires storage in a flammable
safety cabinet?
A) Corrosive acids
B) Oxidizers
C) Flammable liquids with a flash point below 100°F
D) Toxic solids
**ANSWER:** C
,**EXPLANATION:** Flammable liquids with a flash point below 100°F (37.8°C) must be
stored in approved flammable storage cabinets to reduce fire risk.
**QUESTION 3:**
Which of the following is the correct formula for calculating percent recovery in a matrix
spike sample?
A) \( \frac{\text{Spiked sample result} - \text{Unspiked sample result}}{\text{Concentration
of spike added}} \times 100 \)
B) \( \frac{\text{Unspiked sample result}}{\text{Spiked sample result}} \times 100 \)
C) \( \frac{\text{Concentration of spike added}}{\text{Spiked sample result}} \times 100 \)
D) \( \frac{\text{Spiked sample result}}{\text{Unspiked sample result}} \times 100 \)
**ANSWER:** A
**EXPLANATION:** Percent recovery evaluates the accuracy of an analytical method in a
specific sample matrix.
**QUESTION 4:**
In the EDTA titrimetric method for hardness determination, which indicator is commonly
used?
A) Phenolphthalein
B) Eriochrome Black T
C) Starch
D) Potassium chromate
**ANSWER:** B
**EXPLANATION:** Eriochrome Black T is a metal ion indicator that is wine-red in the
presence of Ca²⁺ and Mg²⁺ at pH 10, and turns blue when all hardness ions are complexed
by EDTA.
,**QUESTION 5:**
What is the purpose of a Method Detection Limit (MDL) study?
A) To determine the highest concentration that can be accurately measured
B) To establish the minimum concentration of an analyte that can be detected with 99%
confidence
C) To calibrate an instrument for routine analysis
D) To verify analyst proficiency
**ANSWER:** B
**EXPLANATION:** An MDL study determines the minimum concentration at which an
analyte can be reliably detected with 99% confidence level that the concentration is
greater than zero, according to EPA procedures.
**QUESTION 6:**
For total coliform analysis using the membrane filtration method, the standard incubation
temperature and time are:
A) 35°C ± 0.5°C for 24 ± 2 hours
B) 44.5°C for 24 hours
C) 35°C for 48 hours
D) 20°C for 5 days
**ANSWER:** A
**EXPLANATION:** For total coliforms by membrane filtration (Method 9222B), incubation
is at 35°C ± 0.5°C for 24 ± 2 hours.
**QUESTION 7:**
, A sample for lead and copper tap monitoring must be collected as:
A) A first‑flush sample after 6 hours of stagnation
B) A flowing sample from the treatment plant effluent
C) A composite sample over 24 hours
D) A grab sample from a raw water source
**ANSWER:** A
**EXPLANATION:** The Lead and Copper Rule requires first‑draw tap samples collected
after at least 6 hours of stagnation, typically from high‑risk sites.
**QUESTION 8:**
Which of the following is a secondary contaminant under the National Primary Drinking
Water Regulations?
A) Arsenic
B) Nitrate
C) Chloride
D) Total Trihalomethanes
**ANSWER:** C
**EXPLANATION:** Chloride is regulated under Secondary Drinking Water Standards,
which are non‑enforceable guidelines for aesthetic factors.
**QUESTION 9:**
In a colorimetric analysis using a spectrophotometer, if the absorbance reading is above
2.0, the analyst should:
A) Record the result as is
B) Dilute the sample and re‑read, applying the dilution factor
LATEST WITH CORRECT ANSWERS
**QUESTION 1:**
According to the Safe Drinking Water Act (SDWA), what is the Maximum Contaminant Level
Goal (MCLG) defined as?
A) The enforceable limit set as close to the MCLG as feasible
B) The maximum permissible level of a contaminant in water delivered to any user of a
public water system
C) The level of a contaminant in drinking water below which there is no known or expected
risk to health
D) The highest concentration of a contaminant that is allowed in drinking water
**ANSWER:** C
**EXPLANATION:** The MCLG is a non-enforceable health-based goal set at a level where
no known or anticipated adverse health effects occur, allowing for an adequate margin of
safety.
**QUESTION 2:**
In a drinking water laboratory, which class of chemical requires storage in a flammable
safety cabinet?
A) Corrosive acids
B) Oxidizers
C) Flammable liquids with a flash point below 100°F
D) Toxic solids
**ANSWER:** C
,**EXPLANATION:** Flammable liquids with a flash point below 100°F (37.8°C) must be
stored in approved flammable storage cabinets to reduce fire risk.
**QUESTION 3:**
Which of the following is the correct formula for calculating percent recovery in a matrix
spike sample?
A) \( \frac{\text{Spiked sample result} - \text{Unspiked sample result}}{\text{Concentration
of spike added}} \times 100 \)
B) \( \frac{\text{Unspiked sample result}}{\text{Spiked sample result}} \times 100 \)
C) \( \frac{\text{Concentration of spike added}}{\text{Spiked sample result}} \times 100 \)
D) \( \frac{\text{Spiked sample result}}{\text{Unspiked sample result}} \times 100 \)
**ANSWER:** A
**EXPLANATION:** Percent recovery evaluates the accuracy of an analytical method in a
specific sample matrix.
**QUESTION 4:**
In the EDTA titrimetric method for hardness determination, which indicator is commonly
used?
A) Phenolphthalein
B) Eriochrome Black T
C) Starch
D) Potassium chromate
**ANSWER:** B
**EXPLANATION:** Eriochrome Black T is a metal ion indicator that is wine-red in the
presence of Ca²⁺ and Mg²⁺ at pH 10, and turns blue when all hardness ions are complexed
by EDTA.
,**QUESTION 5:**
What is the purpose of a Method Detection Limit (MDL) study?
A) To determine the highest concentration that can be accurately measured
B) To establish the minimum concentration of an analyte that can be detected with 99%
confidence
C) To calibrate an instrument for routine analysis
D) To verify analyst proficiency
**ANSWER:** B
**EXPLANATION:** An MDL study determines the minimum concentration at which an
analyte can be reliably detected with 99% confidence level that the concentration is
greater than zero, according to EPA procedures.
**QUESTION 6:**
For total coliform analysis using the membrane filtration method, the standard incubation
temperature and time are:
A) 35°C ± 0.5°C for 24 ± 2 hours
B) 44.5°C for 24 hours
C) 35°C for 48 hours
D) 20°C for 5 days
**ANSWER:** A
**EXPLANATION:** For total coliforms by membrane filtration (Method 9222B), incubation
is at 35°C ± 0.5°C for 24 ± 2 hours.
**QUESTION 7:**
, A sample for lead and copper tap monitoring must be collected as:
A) A first‑flush sample after 6 hours of stagnation
B) A flowing sample from the treatment plant effluent
C) A composite sample over 24 hours
D) A grab sample from a raw water source
**ANSWER:** A
**EXPLANATION:** The Lead and Copper Rule requires first‑draw tap samples collected
after at least 6 hours of stagnation, typically from high‑risk sites.
**QUESTION 8:**
Which of the following is a secondary contaminant under the National Primary Drinking
Water Regulations?
A) Arsenic
B) Nitrate
C) Chloride
D) Total Trihalomethanes
**ANSWER:** C
**EXPLANATION:** Chloride is regulated under Secondary Drinking Water Standards,
which are non‑enforceable guidelines for aesthetic factors.
**QUESTION 9:**
In a colorimetric analysis using a spectrophotometer, if the absorbance reading is above
2.0, the analyst should:
A) Record the result as is
B) Dilute the sample and re‑read, applying the dilution factor
