CDL HazMat Endorsement Exam Questions & Answers 2026 (11–20)

Question 1

Under 49 CFR, which situation correctly illustrates the regulatory concept that hazmat rules 'communicate risk' through the transport chain?

TheoryPractice · Accepted Answer

Hazard class labels on packages, placards on the vehicle, and proper shipping names on papers work together so anyone handling or responding to the shipment knows the danger present. The FMCSA CDL Manual explains that the HMR create an integrated system — labels, placards, markings, and shipping papers — each layer communicating risk to handlers, drivers, enforcement officers, and emergency responders at every point in the transport chain, fulfilling 49 CFR 171.1's stated purpose.

Question 2

Which hazard class covers materials that are capable of catching fire when exposed to a spark or flame at temperatures at or below 141°F (60.5°C)?

TheoryPractice · Accepted Answer

Class 3 — Flammable Liquids. Under 49 CFR 173.120, Class 3 (Flammable Liquids) are liquids with a flash point at or below 60.5°C (141°F), distinguishing them from the higher flash-point combustible liquids and from solid or gaseous flammable materials in other classes.

Question 3

A driver is hauling oxygen cylinders for industrial use. Under 49 CFR 173.115, compressed non-flammable gases such as oxygen fall under which hazard class and division?

TheoryPractice · Accepted Answer

Class 2, Division 2.2 — Non-Flammable Gas. 49 CFR 173.115 defines Division 2.2 as non-flammable, non-poisonous compressed gases; oxygen in cylinders meets this definition even though it supports combustion, because the gas itself does not ignite.

Question 4

According to the FMCSA CDL manual, how many sides of the vehicle must display the correct hazmat placards?

TheoryPractice · Accepted Answer

All four sides. The FMCSA CDL Hazardous Materials section and 49 CFR 172.516 require that placards be placed on all four sides of the vehicle so they are visible from any direction of approach.

Question 5

Which of the following best describes Class 1 hazardous materials under 49 CFR 173.50?

TheoryPractice · Accepted Answer

Materials that are capable of detonation, deflagration, or rapid combustion due to chemical reaction. 49 CFR 173.50 defines Class 1 (Explosives) as any substance or article designed to produce an explosion or rapid release of gas and heat through chemical reaction, covering Divisions 1.1 through 1.6.

Question 6

A shipment of sodium metal reacts violently when it contacts water and ignites spontaneously in moist air. Under 49 CFR 173.124, this material is most accurately classified as:

TheoryPractice · Accepted Answer

Division 4.3 — Dangerous When Wet. 49 CFR 173.124 defines Division 4.3 (Dangerous When Wet) as materials that, on contact with water, become spontaneously flammable or emit flammable or toxic gases — sodium's violent water reaction places it squarely in this division.

Question 7

Under 49 CFR 172.504, a driver is required to display hazmat placards when the aggregate gross weight of materials in any single hazard class reaches what threshold?

TheoryPractice · Accepted Answer

1,001 pounds. 49 CFR 172.504(c) sets the general placard threshold at 1,001 lbs (454 kg) aggregate gross weight for Table 2 materials in any single hazard class; certain Table 1 materials (like explosives) require placarding in any quantity.

Question 8

Hydrogen peroxide solution at 52% concentration by mass is classified under 49 CFR 173.128 as which division?

TheoryPractice · Accepted Answer

Division 5.1 — Oxidizing Substance. 49 CFR 173.128 places inorganic peroxides such as hydrogen peroxide solutions with oxidizing properties in Division 5.1 (Oxidizers); organic peroxides in Division 5.2 are carbon-based compounds, which hydrogen peroxide is not.

Question 9

A cargo tank is loaded with a material bearing the Class 7 placard. According to the FMCSA CDL manual, what is the primary hazard associated with Class 7 materials?

TheoryPractice · Accepted Answer

They spontaneously emit ionizing radiation that can damage living tissue or electronic equipment. Class 7 (Radioactive) materials, as defined in 49 CFR 173.403, are substances whose specific activity exceeds 70 Bq/g and which emit ionizing radiation (alpha, beta, gamma, or neutron) that poses a direct health and equipment hazard.

Question 10

While reviewing shipping papers, a driver notices a material listed as a Division 6.1, Packing Group I substance. Under 49 CFR 173.132, this means the material:

TheoryPractice · Accepted Answer

Is highly toxic and poses a severe risk of death or serious injury during transport. 49 CFR 173.132 defines Division 6.1 as poisonous/toxic materials; Packing Group I denotes the highest hazard level — substances with oral, dermal, or inhalation LC50/LD50 values indicating severe acute toxicity that could be fatal.

CDL HazMat Endorsement Exam Questions & Answers 2026 (11–20)

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