CDL Hazmat classes and definitions practice questions
20 free practice questions from 49 CFR 171.8 and 173.2. Each answer is explained and linked to the rule it comes from.
CDL Hazmat classes and definitions
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Hazard classes and divisions
1. A shipper is deciding which hazard class to assign a material. Besides the definitional criteria of part 173, which provisions does the 171.8 definition of hazard class say the class is assigned under?
- A. The packing group chosen by the carrier
- B. The provisions of the § 172.101 table
- C. The emergency response information on the shipping paper
- D. The marking on the outer package
Show answer
Answer: B. The provisions of the § 172.101 table
171.8 states: "Hazard class means the category of hazard assigned to a hazardous material under the definitional criteria of part 173 of this subchapter and the provisions of the § 172.101 table." The primary hazard is "the hazard class of a material as assigned in the § 172.101 table."
Source: eCFR: 49 CFR 171.8, Definitions and abbreviations (as of Nov 4, 2026)
2. A material meets the defining criteria for more than one hazard class. Under the 171.8 definition of hazard class, how many hazard classes is it assigned to?
- A. Every class whose criteria it meets
- B. Two, a primary and a secondary class
- C. None until the shipper obtains an approval
- D. Only one
Show answer
Answer: D. Only one
Under 171.8, "A material may meet the defining criteria for more than one hazard class but is assigned to only one hazard class." Its other hazards are subsidiary hazards: "a hazard of a material other than the primary hazard."
Source: eCFR: 49 CFR 171.8, Definitions and abbreviations (as of Nov 4, 2026)
Where each class is defined
3. A shipper needs the criteria for classifying a Division 5.1 oxidizer. Which section does the 173.2 table give for its definitions?
- A. 173.127
- B. 173.115
- C. 173.136
- D. 173.140
Show answer
Answer: A. 173.127
In the 173.2 table, the Division 5.1 row reads "5.1 OXIDIZER" with "173.127" as the 49 CFR reference for definitions.
4. Some rows of the 173.2 table show "None" in the class number column. What do those rows cover?
- A. Combustible liquids
- B. Limited quantity materials
- C. Forbidden materials and forbidden explosives
- D. Materials of trade
Show answer
Answer: C. Forbidden materials and forbidden explosives
The 173.2 table gives the class number "None" for "FORBIDDEN MATERIALS" (173.21) and "FORBIDDEN EXPLOSIVES" (173.54), and the section says the table lists definitions "for classifying hazardous materials, including forbidden materials."
5. Which section does 171.8 point to for definitions relating to radioactive materials?
- A. 173.134
- B. 173.50
- C. 173.403
- D. 173.21
Show answer
Answer: C. 173.403
171.8 states: "Radioactive materials. See § 173.403 of this subchapter for definitions relating to radioactive materials."
Source: eCFR: 49 CFR 171.8, Definitions and abbreviations (as of Nov 4, 2026)
What counts as a hazardous material
6. Under the 171.8 definition of hazardous material, who has determined that the substance or material is capable of posing an unreasonable risk to health, safety, and property when transported in commerce, and designated it as hazardous?
- A. The Secretary of Transportation
- B. The shipper, by signing the shipper's certification
- C. The motor carrier that accepts the material
- D. The manufacturer of the packaging
Show answer
Answer: A. The Secretary of Transportation
171.8 states: "Hazardous material means a substance or material that the Secretary of Transportation has determined is capable of posing an unreasonable risk to health, safety, and property when transported in commerce, and has designated as hazardous under section 5103 of Federal hazardous materials transportation law".
Source: eCFR: 49 CFR 171.8, Definitions and abbreviations (as of Nov 4, 2026)
7. A material is listed in appendix A to 172.101. For it to be a hazardous substance under 171.8, what quantity condition must it meet?
- A. The total on the vehicle must exceed 454 kg (1,001 pounds)
- B. The shipment must contain at least ten packages
- C. Any amount in any package is enough
- D. Its quantity in one package must equal or exceed the reportable quantity (RQ) listed in appendix A
Show answer
Answer: D. Its quantity in one package must equal or exceed the reportable quantity (RQ) listed in appendix A
A hazardous substance must be "in a quantity, in one package, which equals or exceeds the reportable quantity (RQ) listed in the appendix A to § 172.101 of this subchapter".
Source: eCFR: 49 CFR 171.8, Definitions and abbreviations (as of Nov 4, 2026)
8. A solution contains a material identified in appendix B to 172.101 as a severe marine pollutant. What concentration threshold by weight does the 171.8 marine pollutant definition set for it?
- A. Twenty-five percent
- B. One percent
- C. Fifty percent
- D. Five percent
Show answer
Answer: B. One percent
The threshold is "One percent by weight of the solution or mixture for materials that are identified as severe marine pollutants in the appendix." Ten percent applies to other listed materials.
Source: eCFR: 49 CFR 171.8, Definitions and abbreviations (as of Nov 4, 2026)
9. A liquid with a flash point of 50 °C (122 °F) is intentionally heated and offered for transportation in a bulk packaging at 60 °C (140 °F). How does the 171.8 elevated temperature material definition apply?
- A. It meets the definition, because it is a liquid with a flash point at or above 38 °C (100 °F) that is intentionally heated and offered at or above its flash point
- B. It does not meet the definition, because a liquid must be at or above 100 °C (212 °F) in every case
- C. It does not meet the definition, because only solids can be elevated temperature materials
- D. It does not meet the definition, because the definition covers only non-bulk packagings
Show answer
Answer: A. It meets the definition, because it is a liquid with a flash point at or above 38 °C (100 °F) that is intentionally heated and offered at or above its flash point
An elevated temperature material, in a bulk packaging, includes one that "Is in a liquid phase with a flash point at or above 38 °C (100 °F) that is intentionally heated and offered for transportation or transported at or above its flash point".
Source: eCFR: 49 CFR 171.8, Definitions and abbreviations (as of Nov 4, 2026)
10. Under 171.8, which kind of hazardous material is left out of the definition of material of trade?
- A. Material carried to support the operation or maintenance of the motor vehicle
- B. Material carried to protect the health and safety of the operator or passengers
- C. Material carried by a private motor carrier in direct support of a principal business other than transportation by motor vehicle
- D. Hazardous waste
Show answer
Answer: D. Hazardous waste
171.8 defines material of trade as "a hazardous material, other than a hazardous waste, that is carried on a motor vehicle" for one of three listed purposes, and the other three options are those purposes.
Source: eCFR: 49 CFR 171.8, Definitions and abbreviations (as of Nov 4, 2026)
Bulk and non-bulk packaging
11. Under the 171.8 definition, which of these can be a bulk packaging?
- A. A barge
- B. A transport vehicle or freight container in which hazardous materials are loaded with no intermediate form of containment
- C. A vessel
- D. A packaging with a maximum capacity of 200 L (53 gallons) as a receptacle for a liquid
Show answer
Answer: B. A transport vehicle or freight container in which hazardous materials are loaded with no intermediate form of containment
Bulk packaging is "a packaging, other than a vessel or a barge, including a transport vehicle or freight container, in which hazardous materials are loaded with no intermediate form of containment." A liquid receptacle of "450 L (119 gallons) or less" is a non-bulk packaging.
Source: eCFR: 49 CFR 171.8, Definitions and abbreviations (as of Nov 4, 2026)
12. For a receptacle for a solid, what size condition does the 171.8 definition of bulk packaging set?
- A. A water capacity greater than 454 kg (1000 pounds)
- B. Either a maximum net mass greater than 400 kg (882 pounds) or any capacity
- C. A maximum net mass greater than 400 kg (882 pounds) and a maximum capacity greater than 450 L (119 gallons)
- D. A maximum capacity greater than 450 L (119 gallons), whatever its net mass
Show answer
Answer: C. A maximum net mass greater than 400 kg (882 pounds) and a maximum capacity greater than 450 L (119 gallons)
For a solid, a bulk packaging has "A maximum net mass greater than 400 kg (882 pounds) and a maximum capacity greater than 450 L (119 gallons) as a receptacle for a solid". The water capacity test is for a gas.
Source: eCFR: 49 CFR 171.8, Definitions and abbreviations (as of Nov 4, 2026)
13. A single consignor stacks four drums of a hazardous material on a pallet and secures them with stretch wrap for convenience in handling. What does 171.8 call the wrapped pallet load?
- A. An overpack
- B. A bulk packaging
- C. A freight container
- D. A cargo tank
Show answer
Answer: A. An overpack
An overpack is "an enclosure that is used by a single consignor to provide protection or convenience in handling of a package or to consolidate two or more packages", and examples include packages "Placed or stacked onto a load board such as a pallet and secured by strapping, shrink wrapping, stretch wrapping, or other suitable means". It "does not include a transport vehicle, freight container, or aircraft unit load device."
Source: eCFR: 49 CFR 171.8, Definitions and abbreviations (as of Nov 4, 2026)
Vehicles, containers and tanks
14. How does the 171.8 definition of transport vehicle treat each cargo-carrying body, such as each trailer in a combination?
- A. As one part of a single transport vehicle with the power unit
- B. As a freight container
- C. As a separate transport vehicle
- D. As a cargo tank, whatever its design
Show answer
Answer: C. As a separate transport vehicle
171.8 states: "Each cargo-carrying body (trailer, rail car, etc.) is a separate transport vehicle."
Source: eCFR: 49 CFR 171.8, Definitions and abbreviations (as of Nov 4, 2026)
15. Which description matches the attachment condition in paragraph (2) of the 171.8 cargo tank definition?
- A. The tank must be welded to the frame of a motor vehicle, with no other arrangement allowed
- B. The tank must be lifted off the motor vehicle for loading and unloading
- C. The tank must be fabricated under a specification for portable tanks
- D. The tank is permanently attached to or forms part of a motor vehicle, or is not permanently attached but, by reason of its size, construction or attachment, is loaded or unloaded without being removed from the motor vehicle
Show answer
Answer: D. The tank is permanently attached to or forms part of a motor vehicle, or is not permanently attached but, by reason of its size, construction or attachment, is loaded or unloaded without being removed from the motor vehicle
Paragraph (2) covers a tank that "Is permanently attached to or forms a part of a motor vehicle, or is not permanently attached to a motor vehicle but which, by reason of its size, construction or attachment to a motor vehicle is loaded or unloaded without being removed from the motor vehicle". Paragraph (3) excludes tanks "fabricated under a specification for" portable tanks, among others.
Source: eCFR: 49 CFR 171.8, Definitions and abbreviations (as of Nov 4, 2026)
Offerors, carriers and hazmat employees
16. As a condition of accepting a hazardous material, a carrier reviews the shipping papers and examines the packages. Under 171.8, does that make the carrier an offeror?
- A. Yes. Reviewing a shipping paper is a pre-transportation function, so the carrier always becomes an offeror
- B. No. A carrier is not an offeror when it performs a function required as a condition of acceptance
- C. Yes, but only if the load is placarded
- D. Yes, but only for bulk packagings
Show answer
Answer: B. No. A carrier is not an offeror when it performs a function required as a condition of acceptance
171.8 states: "A carrier is not an offeror when it performs a function required by this subchapter as a condition of acceptance of a hazardous material for transportation in commerce (e.g., reviewing shipping papers, examining packages".
Source: eCFR: 49 CFR 171.8, Definitions and abbreviations (as of Nov 4, 2026)
17. Which self-employed person does the 171.8 definition of hazmat employee include?
- A. No one. Only persons employed by a hazmat employer are hazmat employees
- B. Only a self-employed person who holds a hazardous materials endorsement
- C. Only a self-employed person who employs at least one other worker
- D. An owner-operator of a motor vehicle transporting hazardous materials in commerce who in the course of self-employment directly affects hazardous materials transportation safety
Show answer
Answer: D. An owner-operator of a motor vehicle transporting hazardous materials in commerce who in the course of self-employment directly affects hazardous materials transportation safety
A hazmat employee includes a person who is "Self-employed (including an owner-operator of a motor vehicle, vessel, or aircraft) transporting hazardous materials in commerce who in the course of such self-employment directly affects hazardous materials transportation safety".
Source: eCFR: 49 CFR 171.8, Definitions and abbreviations (as of Nov 4, 2026)
18. A State highway authority transports hazardous materials in commerce using its own employees. Under 171.8, can it be a hazmat employer?
- A. Yes. The definition includes an authority of a State that transports hazardous materials in commerce
- B. No. Only federal agencies are named in the definition
- C. Only if it holds a special permit
- D. No. Only private companies can be hazmat employers
Show answer
Answer: A. Yes. The definition includes an authority of a State that transports hazardous materials in commerce
Paragraph (3) of the hazmat employer definition covers "A department, agency, or instrumentality of the United States Government, or an authority of a State, political subdivision of a State, or an Indian tribe" that, among other things, "Transports hazardous materials in commerce".
Source: eCFR: 49 CFR 171.8, Definitions and abbreviations (as of Nov 4, 2026)
Transportation and related functions
19. Before a shipment is offered, a shipper's employee determines the hazard class of the material. How does 171.8 classify that task?
- A. Loading incidental to movement
- B. Storage incidental to movement
- C. A pre-transportation function
- D. Unloading incidental to movement
Show answer
Answer: C. A pre-transportation function
The 171.8 list of pre-transportation functions begins with "Determining the hazard class of a hazardous material." The three incidental-to-movement terms cover loading, storing and unloading the material in transportation.
Source: eCFR: 49 CFR 171.8, Definitions and abbreviations (as of Nov 4, 2026)
20. How does 171.8 treat storage of a hazardous material at its final destination as shown on a shipping document?
- A. It counts as storage incidental to movement until the carrier leaves
- B. It is not storage incidental to movement
- C. It counts as loading incidental to movement
- D. It counts as storage incidental to movement only for cargo tanks
Show answer
Answer: B. It is not storage incidental to movement
171.8 states: "Storage incidental to movement does not include storage of a hazardous material at its final destination as shown on a shipping document."
Source: eCFR: 49 CFR 171.8, Definitions and abbreviations (as of Nov 4, 2026)