CWEA LABORATORY ANALYST GRADE 2 EXAMINATION |
NEWEST EVALUATED 100% COMPLETE ORIGINAL PRACTICE
EXAMINATION — 120 MULTIPLE-CHOICE QUESTIONS WITH
DETAILED ANSWERS AND RATIONALES| GUARANTEED PASS
GRADE A+ | CURRENTLY UPDATED !! (KEY RELIABLE
SOLUTIONS)
1. Which practice is most effective for preventing cross-contamination when
collecting samples from multiple wastewater locations?
A. Collecting all samples in one large container
B. Using the same sampling equipment without cleaning it
C. Cleaning or replacing sampling equipment between locations
D. Adding preservative before collecting every sample
Correct Answer: C. Cleaning or replacing sampling equipment between locations
Rationale: Cleaning or replacing sampling equipment between sampling
locations minimizes carryover of contaminants and helps preserve the integrity
of each sample.
2. A laboratory analyst discovers that a reagent has exceeded its expiration
date. What should the analyst do?
A. Use it if the reagent appears clear
B. Use it for routine samples but not quality-control samples
,C. Relabel it with a new expiration date
D. Remove it from service and replace it with acceptable reagent
Correct Answer: D. Remove it from service and replace it with acceptable
reagent
Rationale: Expired reagents may have altered chemical properties and can
produce unreliable analytical results.
3. Which document provides instructions for performing a specific laboratory
procedure?
A. Chain-of-custody form
B. Standard operating procedure
C. Sample receipt log
D. Corrective-action report
Correct Answer: B. Standard operating procedure
Rationale: An SOP establishes the standardized steps, equipment, reagents,
calculations, and quality-control requirements for an analytical procedure.
4. Why should laboratory personnel avoid mouth pipetting?
A. It increases evaporation
B. It can introduce microorganisms into samples
C. It creates a serious risk of chemical exposure or ingestion
D. It reduces pipette accuracy
,Correct Answer: C. It creates a serious risk of chemical exposure or ingestion
Rationale: Mouth pipetting can result in accidental ingestion or exposure to
hazardous chemicals and biological materials and is prohibited in proper
laboratory practice.
5. What is the primary purpose of a laboratory quality assurance program?
A. To increase sample volume
B. To ensure analytical results are reliable and defensible
C. To reduce the number of laboratory records
D. To eliminate the need for calibration
Correct Answer: B. To ensure analytical results are reliable and defensible
Rationale: Quality assurance establishes systematic controls that support
accuracy, precision, traceability, and defensibility of laboratory data.
6. A laboratory balance gives slightly different readings when the same mass is
weighed repeatedly. This condition primarily indicates poor:
A. Precision
B. Selectivity
C. Sensitivity
D. Recovery
Correct Answer: A. Precision
, Rationale: Precision describes how closely repeated measurements agree with
one another.
7. Accuracy refers to the:
A. Agreement among repeated measurements
B. Closeness of a measurement to the accepted true value
C. Number of significant figures reported
D. Speed at which an analysis is completed
Correct Answer: B. Closeness of a measurement to the accepted true value
Rationale: Accuracy measures how close a measured result is to the accepted or
reference value.
8. Which item is most appropriate for documenting a deviation from an
established laboratory procedure?
A. Corrective-action record
B. Sample bottle
C. Calibration weight
D. Reagent label
Correct Answer: A. Corrective-action record
Rationale: Corrective-action documentation records the deviation, investigation,
cause, and actions taken to prevent recurrence.
NEWEST EVALUATED 100% COMPLETE ORIGINAL PRACTICE
EXAMINATION — 120 MULTIPLE-CHOICE QUESTIONS WITH
DETAILED ANSWERS AND RATIONALES| GUARANTEED PASS
GRADE A+ | CURRENTLY UPDATED !! (KEY RELIABLE
SOLUTIONS)
1. Which practice is most effective for preventing cross-contamination when
collecting samples from multiple wastewater locations?
A. Collecting all samples in one large container
B. Using the same sampling equipment without cleaning it
C. Cleaning or replacing sampling equipment between locations
D. Adding preservative before collecting every sample
Correct Answer: C. Cleaning or replacing sampling equipment between locations
Rationale: Cleaning or replacing sampling equipment between sampling
locations minimizes carryover of contaminants and helps preserve the integrity
of each sample.
2. A laboratory analyst discovers that a reagent has exceeded its expiration
date. What should the analyst do?
A. Use it if the reagent appears clear
B. Use it for routine samples but not quality-control samples
,C. Relabel it with a new expiration date
D. Remove it from service and replace it with acceptable reagent
Correct Answer: D. Remove it from service and replace it with acceptable
reagent
Rationale: Expired reagents may have altered chemical properties and can
produce unreliable analytical results.
3. Which document provides instructions for performing a specific laboratory
procedure?
A. Chain-of-custody form
B. Standard operating procedure
C. Sample receipt log
D. Corrective-action report
Correct Answer: B. Standard operating procedure
Rationale: An SOP establishes the standardized steps, equipment, reagents,
calculations, and quality-control requirements for an analytical procedure.
4. Why should laboratory personnel avoid mouth pipetting?
A. It increases evaporation
B. It can introduce microorganisms into samples
C. It creates a serious risk of chemical exposure or ingestion
D. It reduces pipette accuracy
,Correct Answer: C. It creates a serious risk of chemical exposure or ingestion
Rationale: Mouth pipetting can result in accidental ingestion or exposure to
hazardous chemicals and biological materials and is prohibited in proper
laboratory practice.
5. What is the primary purpose of a laboratory quality assurance program?
A. To increase sample volume
B. To ensure analytical results are reliable and defensible
C. To reduce the number of laboratory records
D. To eliminate the need for calibration
Correct Answer: B. To ensure analytical results are reliable and defensible
Rationale: Quality assurance establishes systematic controls that support
accuracy, precision, traceability, and defensibility of laboratory data.
6. A laboratory balance gives slightly different readings when the same mass is
weighed repeatedly. This condition primarily indicates poor:
A. Precision
B. Selectivity
C. Sensitivity
D. Recovery
Correct Answer: A. Precision
, Rationale: Precision describes how closely repeated measurements agree with
one another.
7. Accuracy refers to the:
A. Agreement among repeated measurements
B. Closeness of a measurement to the accepted true value
C. Number of significant figures reported
D. Speed at which an analysis is completed
Correct Answer: B. Closeness of a measurement to the accepted true value
Rationale: Accuracy measures how close a measured result is to the accepted or
reference value.
8. Which item is most appropriate for documenting a deviation from an
established laboratory procedure?
A. Corrective-action record
B. Sample bottle
C. Calibration weight
D. Reagent label
Correct Answer: A. Corrective-action record
Rationale: Corrective-action documentation records the deviation, investigation,
cause, and actions taken to prevent recurrence.
