NFPA CLSS - HC EXAM | QUESTIONS AND 100%
CORRECT ANSWERS WITH RATIONALES | LATEST
UPDATE GRADED A+
1. Which of the following is the most important initial step in laboratory chemical spill
response?
A. Evacuate the area
B. Contain the spill immediately
C. Notify the supervisor
D. Neutralize the chemical
Answer: A. Evacuate the area
Rationale: Ensuring personal safety by evacuating is always the first priority before
attempting containment or cleanup.
2. The NFPA diamond blue section represents:
A. Reactivity
B. Health hazard
C. Flammability
D. Special hazard
Answer: B. Health hazard
Rationale: The blue section indicates the level of health hazard posed by the chemical, with
higher numbers indicating greater risk.
3. Which class of fire extinguisher should be used on an electrical fire?
A. Class A
B. Class B
C. Class C
D. Class D
Answer: C. Class C
Rationale: Class C extinguishers are specifically designed for fires involving energized
electrical equipment.
4. In a healthcare laboratory, the term SDS stands for:
A. Safety Data Sheet
B. Standard Disposal System
C. Safety Documentation Standard
D. Sample Decontamination Sheet
Answer: A. Safety Data Sheet
Rationale: SDS provides essential information about chemical hazards, handling, storage,
and emergency measures.
, 5. Which of the following PPE is mandatory when handling corrosive chemicals?
A. Lab coat and gloves
B. Safety goggles and face shield
C. Respirator
D. All of the above
Answer: D. All of the above
Rationale: Proper protection requires covering skin, eyes, and respiratory exposure when
dealing with corrosives.
6. The red section of the NFPA diamond indicates:
A. Flammability
B. Health hazard
C. Reactivity
D. Specific hazard
Answer: A. Flammability
Rationale: Red indicates the fire hazard of a chemical, showing how easily it can ignite.
7. Which fire class involves combustible metals like magnesium?
A. Class A
B. Class B
C. Class C
D. Class D
Answer: D. Class D
Rationale: Class D fires involve combustible metals and require specialized extinguishing
agents.
8. The term “biohazard” refers to:
A. Any chemical that is toxic
B. Biological substances that pose a risk to humans
C. Any flammable material
D. Radioactive waste
Answer: B. Biological substances that pose a risk to humans
Rationale: Biohazards include infectious agents like bacteria, viruses, and other
microorganisms that can cause disease.
9. Which color in the NFPA diamond represents reactivity?
A. Blue
B. Red
C. Yellow
D. White
Answer: C. Yellow
Rationale: Yellow indicates the chemical’s reactivity or stability, helping identify explosive or
unstable compounds.
, 10. Which of the following is a universal precaution in clinical labs?
A. Wearing gloves when handling all specimens
B. Only washing hands after spills
C. Sharing pipettes between samples
D. Using open flames freely
Answer: A. Wearing gloves when handling all specimens
Rationale: Universal precautions assume all specimens could be infectious, so gloves and
PPE are mandatory.
11. What is the primary purpose of the white section on the NFPA diamond?
A. Health hazard
B. Flammability
C. Special hazards
D. Reactivity
Answer: C. Special hazards
Rationale: White indicates unique hazards such as oxidizers, acids, or radiation warnings.
12. In case of a mercury spill, the correct cleanup material is:
A. Paper towels
B. Wet mop
C. Mercury-specific absorbent
D. Sand
Answer: C. Mercury-specific absorbent
Rationale: Mercury is toxic, and only specialized cleanup kits safely remove it without
spreading vapors.
13. A chemical with NFPA rating 4 in red is:
A. Slightly flammable
B. Moderately flammable
C. Extremely flammable
D. Non-flammable
Answer: C. Extremely flammable
Rationale: A rating of 4 indicates the highest flammability risk.
14. Which type of eyewash station is required in labs handling corrosive substances?
A. Plumbed eyewash with continuous flow
B. Bottled eyewash
C. Handheld spray
D. No eyewash needed
Answer: A. Plumbed eyewash with continuous flow
Rationale: Continuous flow eyewash ensures thorough flushing in case of chemical splashes
to the eyes.
, 15. The term “fume hood” refers to:
A. A storage cabinet for chemicals
B. A ventilation device to remove hazardous fumes
C. A PPE item
D. A fire suppression system
Answer: B. A ventilation device to remove hazardous fumes
Rationale: Fume hoods protect lab personnel by removing toxic vapors from the breathing
zone.
16. When using a centrifuge, what is the most important safety step?
A. Balancing the tubes
B. Using open flames nearby
C. Overfilling tubes
D. Wearing sandals
Answer: A. Balancing the tubes
Rationale: Proper balancing prevents equipment damage and potential accidents.
17. Which NFPA rating number indicates minimal hazard?
A. 0
B. 1
C. 2
D. 4
Answer: A. 0
Rationale: The NFPA scale ranges from 0 (minimal) to 4 (severe hazard).
18. What is the primary route of exposure for airborne pathogens in labs?
A. Skin contact
B. Inhalation
C. Ingestion
D. Eye irritation
Answer: B. Inhalation
Rationale: Airborne pathogens can be inhaled, making respiratory protection critical.
19. Which of the following is a Class B fire?
A. Wood fire
B. Gasoline fire
C. Electrical fire
D. Magnesium fire
Answer: B. Gasoline fire
Rationale: Class B fires involve flammable liquids like gasoline, oil, and solvents.
20. Standard precautions in handling blood specimens include:
CORRECT ANSWERS WITH RATIONALES | LATEST
UPDATE GRADED A+
1. Which of the following is the most important initial step in laboratory chemical spill
response?
A. Evacuate the area
B. Contain the spill immediately
C. Notify the supervisor
D. Neutralize the chemical
Answer: A. Evacuate the area
Rationale: Ensuring personal safety by evacuating is always the first priority before
attempting containment or cleanup.
2. The NFPA diamond blue section represents:
A. Reactivity
B. Health hazard
C. Flammability
D. Special hazard
Answer: B. Health hazard
Rationale: The blue section indicates the level of health hazard posed by the chemical, with
higher numbers indicating greater risk.
3. Which class of fire extinguisher should be used on an electrical fire?
A. Class A
B. Class B
C. Class C
D. Class D
Answer: C. Class C
Rationale: Class C extinguishers are specifically designed for fires involving energized
electrical equipment.
4. In a healthcare laboratory, the term SDS stands for:
A. Safety Data Sheet
B. Standard Disposal System
C. Safety Documentation Standard
D. Sample Decontamination Sheet
Answer: A. Safety Data Sheet
Rationale: SDS provides essential information about chemical hazards, handling, storage,
and emergency measures.
, 5. Which of the following PPE is mandatory when handling corrosive chemicals?
A. Lab coat and gloves
B. Safety goggles and face shield
C. Respirator
D. All of the above
Answer: D. All of the above
Rationale: Proper protection requires covering skin, eyes, and respiratory exposure when
dealing with corrosives.
6. The red section of the NFPA diamond indicates:
A. Flammability
B. Health hazard
C. Reactivity
D. Specific hazard
Answer: A. Flammability
Rationale: Red indicates the fire hazard of a chemical, showing how easily it can ignite.
7. Which fire class involves combustible metals like magnesium?
A. Class A
B. Class B
C. Class C
D. Class D
Answer: D. Class D
Rationale: Class D fires involve combustible metals and require specialized extinguishing
agents.
8. The term “biohazard” refers to:
A. Any chemical that is toxic
B. Biological substances that pose a risk to humans
C. Any flammable material
D. Radioactive waste
Answer: B. Biological substances that pose a risk to humans
Rationale: Biohazards include infectious agents like bacteria, viruses, and other
microorganisms that can cause disease.
9. Which color in the NFPA diamond represents reactivity?
A. Blue
B. Red
C. Yellow
D. White
Answer: C. Yellow
Rationale: Yellow indicates the chemical’s reactivity or stability, helping identify explosive or
unstable compounds.
, 10. Which of the following is a universal precaution in clinical labs?
A. Wearing gloves when handling all specimens
B. Only washing hands after spills
C. Sharing pipettes between samples
D. Using open flames freely
Answer: A. Wearing gloves when handling all specimens
Rationale: Universal precautions assume all specimens could be infectious, so gloves and
PPE are mandatory.
11. What is the primary purpose of the white section on the NFPA diamond?
A. Health hazard
B. Flammability
C. Special hazards
D. Reactivity
Answer: C. Special hazards
Rationale: White indicates unique hazards such as oxidizers, acids, or radiation warnings.
12. In case of a mercury spill, the correct cleanup material is:
A. Paper towels
B. Wet mop
C. Mercury-specific absorbent
D. Sand
Answer: C. Mercury-specific absorbent
Rationale: Mercury is toxic, and only specialized cleanup kits safely remove it without
spreading vapors.
13. A chemical with NFPA rating 4 in red is:
A. Slightly flammable
B. Moderately flammable
C. Extremely flammable
D. Non-flammable
Answer: C. Extremely flammable
Rationale: A rating of 4 indicates the highest flammability risk.
14. Which type of eyewash station is required in labs handling corrosive substances?
A. Plumbed eyewash with continuous flow
B. Bottled eyewash
C. Handheld spray
D. No eyewash needed
Answer: A. Plumbed eyewash with continuous flow
Rationale: Continuous flow eyewash ensures thorough flushing in case of chemical splashes
to the eyes.
, 15. The term “fume hood” refers to:
A. A storage cabinet for chemicals
B. A ventilation device to remove hazardous fumes
C. A PPE item
D. A fire suppression system
Answer: B. A ventilation device to remove hazardous fumes
Rationale: Fume hoods protect lab personnel by removing toxic vapors from the breathing
zone.
16. When using a centrifuge, what is the most important safety step?
A. Balancing the tubes
B. Using open flames nearby
C. Overfilling tubes
D. Wearing sandals
Answer: A. Balancing the tubes
Rationale: Proper balancing prevents equipment damage and potential accidents.
17. Which NFPA rating number indicates minimal hazard?
A. 0
B. 1
C. 2
D. 4
Answer: A. 0
Rationale: The NFPA scale ranges from 0 (minimal) to 4 (severe hazard).
18. What is the primary route of exposure for airborne pathogens in labs?
A. Skin contact
B. Inhalation
C. Ingestion
D. Eye irritation
Answer: B. Inhalation
Rationale: Airborne pathogens can be inhaled, making respiratory protection critical.
19. Which of the following is a Class B fire?
A. Wood fire
B. Gasoline fire
C. Electrical fire
D. Magnesium fire
Answer: B. Gasoline fire
Rationale: Class B fires involve flammable liquids like gasoline, oil, and solvents.
20. Standard precautions in handling blood specimens include:
