CDL Hazmat marking practice questions
20 free practice questions from 49 CFR Part 172 Subpart D. Each answer is explained and linked to the rule it comes from.
CDL Hazmat marking
20 questions across 8 topics. After each answer you see why it is right, with a link to the official source.
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Who marks and general rules
1. Under 172.300, when must a carrier that transports a hazardous material mark the packages, freight containers and transport vehicles?
- A. Only when the shipper asks the carrier in writing
- B. When Subpart D assigns the function to the carrier
- C. Never; only the consignee may mark them
- D. Only when the shipment crosses a state line
Show answer
Answer: B. When Subpart D assigns the function to the carrier
172.300(b): "When assigned the function by this subpart, each carrier that transports a hazardous material shall mark each package, freight container, and transport vehicle containing the hazardous material in the manner required by this subpart."
Source: eCFR: 49 CFR 172.300, Applicability (as of Nov 4, 2026)
2. A package still bears a hazardous material's proper shipping name but holds no hazardous material or residue. Which situation does 172.303(b)(1) exclude from the prohibited-marking rule?
- A. The package travels less than 100 miles
- B. The driver notes the old marking on the shipping paper
- C. The package is not visible during transportation in a transport vehicle and is loaded by the shipper and unloaded by the shipper or consignee
- D. The package weighs less than 30 kg (66 pounds)
Show answer
Answer: C. The package is not visible during transportation in a transport vehicle and is loaded by the shipper and unloaded by the shipper or consignee
The rule does not apply to "Transportation of a package in a transport vehicle or freight container if the package is not visible during transportation and is loaded by the shipper and unloaded by the shipper or consignee."
Source: eCFR: 49 CFR 172.303, Prohibited marking (as of Nov 4, 2026)
Non-bulk packages
3. A trailer holds 5,000 kg of one hazardous material (not Class 1 or Class 7) in non-bulk packages, all marked with the same proper shipping name and ID number, and no other cargo. Half was loaded at one facility and half at a second facility. Does 172.301(a)(3) require the ID number on each side and each end?
- A. No, because one of its conditions is that all of the hazardous material is loaded at one loading facility
- B. Yes, because the aggregate gross weight is 4,000 kg (8,820 pounds) or more
- C. Yes, because every vehicle carrying non-bulk packages must show ID numbers
- D. No, because 172.301(a)(3) covers only bulk packagings
Show answer
Answer: A. No, because one of its conditions is that all of the hazardous material is loaded at one loading facility
172.301(a)(3) applies "subject to the following provisions and limitations", which include "All of the hazardous material is loaded at one loading facility" and "The transport vehicle or freight container contains no other material, hazardous or otherwise".
Source: eCFR: 49 CFR 172.301, General marking requirements for non-bulk packagings (as of Nov 4, 2026)
4. Which material does 172.301(a)(3) leave out of its rule that a vehicle carrying a large quantity of a single hazardous material in non-bulk packages be marked with the ID number?
- A. Class 3 flammable liquids
- B. Class 8 corrosive materials
- C. Class 7 radioactive materials
- D. Division 2.2 non-flammable gases
Show answer
Answer: C. Class 7 radioactive materials
"The identification number marking requirement of this paragraph (a)(3) does not apply to Class 1, Class 7, or to non-bulk packagings for which identification numbers are not required."
Source: eCFR: 49 CFR 172.301, General marking requirements for non-bulk packagings (as of Nov 4, 2026)
5. When does 172.301(d) excuse a non-bulk hazmat package from being marked with the name and address of the consignor or consignee?
- A. When it is moved by highway and handed from one motor carrier to another
- B. When it travels by rail in a mixed carload from several consignors
- C. When it rides in any placarded vehicle
- D. When it is transported by highway only and will not be transferred from one motor carrier to another
Show answer
Answer: D. When it is transported by highway only and will not be transferred from one motor carrier to another
The marking is required "except when the package is— (1) Transported by highway only and will not be transferred from one motor carrier to another".
Source: eCFR: 49 CFR 172.301, General marking requirements for non-bulk packagings (as of Nov 4, 2026)
6. A trailer must show one ID number under 172.313(c) for materials poisonous by inhalation in non-bulk packages, and it carries one Hazard Zone A material and one Hazard Zone B material. Whose ID number is shown?
- A. The Hazard Zone A material's
- B. The material with the greatest aggregate gross weight, whatever its zone
- C. The Hazard Zone B material's
- D. Neither; the trailer shows the word INHALATION HAZARD instead
Show answer
Answer: A. The Hazard Zone A material's
When more than one such material is aboard, it is marked "For different materials in both Hazard Zones A and B, with the identification number for the Hazard Zone A material."
Source: eCFR: 49 CFR 172.313, Poisonous hazardous materials (as of Nov 4, 2026)
Hazard-specific package marks
7. Which non-bulk package does 172.312(c) exclude from the package orientation (upright arrows) marking rule?
- A. A non-bulk package with inner packagings which are cylinders
- B. A single packaging fitted with vents
- C. An open cryogenic receptacle for refrigerated liquefied gases
- D. A combination package with 5 L inner jugs of corrosive liquid
Show answer
Answer: A. A non-bulk package with inner packagings which are cylinders
The orientation requirements "do not apply to— (1) A non-bulk package with inner packagings which are cylinders."
Source: eCFR: 49 CFR 172.312, Liquid hazardous materials in non-bulk packagings (as of Nov 4, 2026)
8. A non-bulk package holds a hazardous substance whose proper shipping name does not name that substance. What does 172.324 require on the package?
- A. Only the reportable quantity in pounds, next to the closure
- B. The name of the hazardous substance in parentheses with the proper shipping name, and the letters RQ with the proper shipping name
- C. The words HAZARDOUS SUBSTANCE on every side
- D. The EPA identification number of the shipper
Show answer
Answer: B. The name of the hazardous substance in parentheses with the proper shipping name, and the letters RQ with the proper shipping name
"The name of the hazardous substance must be marked on the package, in parentheses, in association with the proper shipping name", and "The letters “RQ” must be marked on the package in association with the proper shipping name."
Source: eCFR: 49 CFR 172.324, Hazardous substances in non-bulk packagings (as of Nov 4, 2026)
9. When does 172.313(a) say the "Inhalation Hazard" marking is not required on a package of a material poisonous by inhalation?
- A. When the package is a bulk packaging
- B. When it moves by private motor carrier
- C. When the package weighs under 30 kg (66 pounds)
- D. When the words "Inhalation Hazard" appear on the label or placard
Show answer
Answer: D. When the words "Inhalation Hazard" appear on the label or placard
"When the words “Inhalation Hazard” appear on the label ... or placard ... the “Inhalation Hazard” marking is not required on the package."
Source: eCFR: 49 CFR 172.313, Poisonous hazardous materials (as of Nov 4, 2026)
Bulk packages
10. Under 172.302(d), which is one condition under which an emptied bulk packaging that was marked with a proper shipping name or ID number no longer has to remain marked?
- A. As soon as it is unloaded at the consignee
- B. When it is returned to the shipper's yard
- C. When the driver records it as empty on the shipping paper
- D. When it is sufficiently cleaned of residue and purged of vapors to remove any potential hazard
Show answer
Answer: D. When it is sufficiently cleaned of residue and purged of vapors to remove any potential hazard
It "must remain marked when it is emptied unless it is— (1) Sufficiently cleaned of residue and purged of vapors to remove any potential hazard; or (2) Refilled" with a material whose residue is then no longer hazardous.
Source: eCFR: 49 CFR 172.302, General marking requirements for bulk packagings (as of Nov 4, 2026)
11. A bulk packaging contains molten sulfur. How does 172.325 say it must be marked?
- A. MOLTEN SULFUR, in the same manner as the HOT marking
- B. HOT on the rear end only
- C. ELEVATED TEMPERATURE on every side
- D. Only with the shipper's name and address
Show answer
Answer: A. MOLTEN SULFUR, in the same manner as the HOT marking
"Bulk packagings containing molten aluminum or molten sulfur must be marked “MOLTEN ALUMINUM” or “MOLTEN SULFUR”, respectively, in the same manner as prescribed in paragraph (a) of this section."
Source: eCFR: 49 CFR 172.325, Elevated temperature materials (as of Nov 4, 2026)
Portable tanks, IBCs and other bulk packagings
12. A portable tank of hazardous material is loaded in a trailer so that its ID numbers cannot be seen from some sides. Under 172.326(c)(2), who must give the motor carrier the ID numbers for those sides of the trailer?
- A. The consignee, on arrival
- B. The tank manufacturer
- C. The person who offers the portable tank to the motor carrier
- D. The driver, who must paint them on by hand
Show answer
Answer: C. The person who offers the portable tank to the motor carrier
"Each person who offers a portable tank containing a hazardous material to a motor carrier ... shall provide the motor carrier with the required identification numbers on placards, orange panels, or the white square-on-point configuration" for each side and end where the tank's numbers are not visible.
Source: eCFR: 49 CFR 172.326, Portable tanks (as of Nov 4, 2026)
Cargo tanks
13. Under 172.328(a)(1), when must a person offering a hazardous material to a motor carrier for a cargo tank give the identification numbers on placards (or affix orange panels), if the tank is not already marked?
- A. Within 24 hours after the tank leaves the facility
- B. Prior to or at the time the material is offered for transportation
- C. At the first stop after loading
- D. Before the empty return trip
Show answer
Answer: B. Prior to or at the time the material is offered for transportation
The offeror "shall provide the motor carrier the identification numbers on placards or shall affix orange panels containing the required identification numbers, prior to or at the time the material is offered for transportation."
Source: eCFR: 49 CFR 172.328, Cargo tanks (as of Nov 4, 2026)
14. A cargo tank (not a nurse tank) transports a Class 2 gas. What does 172.328(b) require it to be marked with on each side and each end?
- A. The shipper's name and address
- B. The date of the tank's last test
- C. The word GAS and the hazard class number
- D. The proper shipping name of the gas or an appropriate common name for the material
Show answer
Answer: D. The proper shipping name of the gas or an appropriate common name for the material
Each such cargo tank "must be marked, in lettering no less than 50 mm (2.0 inches), on each side and each end with— (1) The proper shipping name specified for the gas in the § 172.101 table; or (2) An appropriate common name for the material (e.g., “Refrigerant Gas”)."
Source: eCFR: 49 CFR 172.328, Cargo tanks (as of Nov 4, 2026)
15. A cargo tank contains only gasoline. Under the table in 172.336(c), what alternative lets it go without identification numbers?
- A. The tank is marked "Gasoline" on each side and rear in letters no less than 50 mm (2 inches) high, or is placarded under 172.542(c)
- B. The driver carries a shipping paper that lists gasoline
- C. The tank holds less than 3,785 L (1,000 gallons)
- D. The tank shows the shipper's name on each side
Show answer
Answer: A. The tank is marked "Gasoline" on each side and rear in letters no less than 50 mm (2 inches) high, or is placarded under 172.542(c)
For cargo tanks that contain only gasoline, the alternative is: "The tank is marked “Gasoline” on each side and rear in letters no less than 50 mm (2 inches) high or is placarded in accordance with § 172.542(c)."
Source: eCFR: 49 CFR 172.336, Identification numbers; special provisions (as of Nov 4, 2026)
Identification number displays
16. A van trailer carries non-bulk packages of two Class 3 materials with different identification numbers. The carrier wants to meet the placarding rules with FLAMMABLE placards bearing the identification number of only one of them. Under 172.334(d), may it?
- A. Yes, if that material makes up most of the load's weight
- B. Yes, if both materials are listed on the shipping paper
- C. No. A placard bearing an ID number may meet subpart F only if it is the correct ID number for all hazardous materials of the same class in the vehicle
- D. Yes, if the driver knows both numbers
Show answer
Answer: C. No. A placard bearing an ID number may meet subpart F only if it is the correct ID number for all hazardous materials of the same class in the vehicle
"Except as provided in § 172.336, a placard bearing an identification number may not be used to meet the requirements of subpart F of this part unless it is the correct identification number for all hazardous materials of the same class in the transport vehicle or freight container on which it is displayed."
Source: eCFR: 49 CFR 172.334, Identification numbers; prohibited display (as of Nov 4, 2026)
17. How does 172.336(b) treat an identification number shown on a white square-on-point display configuration?
- A. It counts as the placard for the material
- B. It replaces the shipping paper
- C. It may be used only on rail cars
- D. It is not considered to be a placard
Show answer
Answer: D. It is not considered to be a placard
"An identification number displayed on a white square-on-point display configuration is not considered to be a placard."
Source: eCFR: 49 CFR 172.336, Identification numbers; special provisions (as of Nov 4, 2026)
18. During a trip, more than one of the required identification number displays on a vehicle are lost or damaged. What does 172.338 provide?
- A. The shipper must replace them before the vehicle moves, and hand entry is not allowed
- B. The carrier must replace them as soon as practicable, and the correct numbers may be entered by hand, legibly, with indelible marking material
- C. The consignee replaces them on arrival
- D. The vehicle may finish the trip without them if the shipping paper shows the numbers
Show answer
Answer: B. The carrier must replace them as soon as practicable, and the correct numbers may be entered by hand, legibly, with indelible marking material
"The carrier shall replace all the missing or damaged identification numbers as soon as practicable. However, in such a case, the numbers may be entered by hand ... providing the correct identification numbers are entered legibly using an indelible marking material."
Source: eCFR: 49 CFR 172.338, Replacement of identification numbers (as of Nov 4, 2026)
Limited quantity and marine pollutant marks
19. A package shows the limited quantity marking and is offered by highway. Under 172.315(a), when is it still subject to the 172.301 marking requirements?
- A. When it rides on a private motor carrier
- B. When it weighs more than 30 kg (66 pounds)
- C. When it also contains a hazardous substance or a hazardous waste
- D. When it is loaded in a closed van
Show answer
Answer: C. When it also contains a hazardous substance or a hazardous waste
"A package displaying this mark is not subject to the marking requirements of § 172.301 of this subpart unless the limited quantity package also contains a hazardous substance or a hazardous waste."
Source: eCFR: 49 CFR 172.315, Limited quantities (as of Nov 4, 2026)
20. A truck carries a portable tank that is marked with the MARINE POLLUTANT mark. Under 172.322(c), how may the truck's own marking requirement be met?
- A. By a note on the shipping paper
- B. By the marking displayed on the portable tank loaded on the motor vehicle
- C. By the driver telling the consignee
- D. By one mark on the cab roof
Show answer
Answer: B. By the marking displayed on the portable tank loaded on the motor vehicle
The mark must appear on each side and each end of the vehicle, and "This requirement may be met by the marking displayed on a freight container or portable tank loaded on a motor vehicle or rail car."
Source: eCFR: 49 CFR 172.322, Marine pollutants (as of Nov 4, 2026)