Iowa Hazmat CDL Practice Test

This is a free 20-question practice test for the Hazmat portion of the Iowa Commercial Driver's License knowledge exam. Questions are pulled from a pool of 68 drawn from the AAMVA CDL Manual, which is the source document the Iowa Department of Transportation Motor Vehicle Division uses to write its actual exam.

How it works: Click an answer. The correct choice highlights in green, and you'll see a short explanation. Aim for 85% or better before you sit for the real test in Iowa.

Question 1 of 20

The Hazmat (H) endorsement requires:

Only a knowledge test
A knowledge test plus a TSA Threat Assessment background check
Just a fee
A skills test only

Correct. Hazmat applicants pass a knowledge test and complete the TSA Threat Assessment (HME), which involves fingerprints and an FBI background check.

Question 2 of 20

When loading a vehicle with hazardous materials, you should:

Set the parking brake, chock the wheels, turn off the engine
Leave the engine running
Smoke if outside the cab
Skip the brake check

Correct. Set the parking brake, chock wheels of cargo tank vehicles, and shut off the engine before loading or unloading flammables.

Question 3 of 20

You discover a leak in a Class 3 (flammable liquid) shipment. You should:

Continue driving until you find a safe place
Stop, secure the area, notify emergency services, do not transfer cargo on the road, do not move the vehicle further than necessary
Drive faster to deliver the load
Open the placards

Correct. Stop in a safe location, secure the area, call 911, and notify your dispatcher. Do not transfer cargo by the side of the road.

Question 4 of 20

A vehicle hauling explosives may not be parked within:

100 feet of an open fire, school, theater, or place where people gather
10 feet of any building
One block of a fire station
Any distance

Correct. Class 1 explosives have specific parking restrictions — at least 300 feet from open fires; never near schools, theaters, or places where people gather.

Question 5 of 20

When tarping hazmat cargo, you must:

Cover the placards
Leave placards visible at all times
Tarp only at night
Use only red tarps

Correct. Placards must remain visible. Tarps and decorations may not block them.

Question 6 of 20

Inhalation hazard placards (Division 6.1 PIH or Division 2.3) require:

Smaller placards
Subsidiary "INHALATION HAZARD" placards in addition to the primary placard
No placards
Only one placard

Correct. PIH (Poison Inhalation Hazard) materials require a primary hazard-class placard plus an "INHALATION HAZARD" subsidiary placard.

Question 7 of 20

When refueling a hazmat-loaded vehicle:

Leave the engine running
Turn off the engine, do not smoke, and someone must control the fueling process
Smoke if you are far enough away
It does not matter

Correct. Engine off, no smoking within 25 feet of the vehicle being fueled, and someone must be in control of the fueling at the nozzle.

Question 8 of 20

A vehicle that has been transporting hazmat may need to be:

Decontaminated and re-placarded as required after unloading
Painted
Sold
Inspected by USCG

Correct. After unloading, the vehicle may need decontamination depending on the cargo. Placards may need to be removed unless residue still requires them.

Question 9 of 20

Subsidiary risk labels on a package indicate:

Additional hazards beyond the primary hazard
Just decoration
The price
The weight

Correct. Some materials have multiple hazards. The primary hazard is shown on the top-class label; subsidiary risks (e.g., toxic AND flammable) are shown on additional labels.

Question 10 of 20

Hazmat drivers must report any change of:

Address to the licensing agency
Daily route
Diet
Vehicle paint color

Correct. Address changes must be reported to the state licensing agency in line with state CDL requirements; some states require reporting within 30 days.

Question 11 of 20

The Emergency Response Guidebook (ERG) is used to:

Plan routes
Look up the four-digit hazmat ID number to find emergency response procedures
Calculate fuel cost
Find truck stops

Correct. The ERG cross-references the four-digit ID number from the placard or shipping paper to a guide page with isolation distance, response procedures, and first aid.

Question 12 of 20

A hazmat driver must complete which special training?

General awareness, function-specific, safety, security awareness, and in-depth security if a security plan is required
Forklift training
Basic first aid only
Defensive driving only

Correct. PHMSA requires general awareness, function-specific, safety, security awareness, and in-depth security training (when a security plan applies). Carriers document and re-train every three years.

Question 13 of 20

Hazard Class 1 is:

Flammable liquids
Explosives
Corrosives
Radioactive materials

Correct. Class 1 covers explosives, divided into divisions 1.1 through 1.6 by mass-explosion and projection hazard.

Question 14 of 20

A driver of a hazmat-loaded vehicle must check the tires:

Once before the trip
At the start of the trip and every time the vehicle is parked
Only at fueling
Never

Correct. Hazmat drivers must check tires at the beginning and again each time the vehicle is parked. A flat or smoking tire must be addressed before continuing.

Question 15 of 20

A driver must understand the hazmat security plan:

Only managers do
Only when it is required for the carrier and the materials being transported, then driver in-depth security training is required
Never
Only on request

Correct. When a security plan is required (Division 1.1, 1.2, 1.3, certain quantities of toxic-by-inhalation, etc.), drivers receive in-depth security training and a copy or summary of the plan.

Question 16 of 20

Hazard Class 3 is:

Flammable liquids
Explosives
Toxic substances
Radioactive

Correct. Class 3 is flammable liquids — gasoline, diesel, ethanol, alcohols, etc.

Question 17 of 20

Drivers of hazmat vehicles must avoid which of the following routes when alternatives exist?

Tunnels, narrow streets, and densely populated areas
Interstates
Highways
Rural routes

Correct. Avoid populated areas, narrow streets, tunnels, and other places where an incident would maximize risk. Follow state-designated hazmat routes.

Question 18 of 20

When carrying hazmat through a state or local jurisdiction with route restrictions, you must:

Comply with the restrictions
Choose the shortest route
Take the highway always
Disregard local rules

Correct. State and local hazmat route restrictions are enforceable. Plan routes that comply with restrictions and avoid prohibited tunnels and bridges.

Question 19 of 20

In a hazmat fire, you should:

Try to extinguish all fires regardless of size
Determine the materials involved using the shipping paper and ERG; only fight small fires that you can safely extinguish
Run
Pour water on every fire

Correct. Identify materials and consult the ERG. Only fight small fires that you can safely extinguish; large fires require professional response. Some materials react violently with water.

Question 20 of 20

You should keep the hazmat shipping paper:

Identifiable and within reach of the driver, marked with a tab or kept on top of other papers
Hidden
In the trailer
Folded inside the manual

Correct. Hazmat shipping papers must be identifiable to emergency responders — tabbed or kept on top of other paperwork, in the seat or door pouch when the driver is out.

About the Iowa Hazmat exam

Most states administer 30 Hazmat questions and require 80% to pass. The exam covers hazard classes, the shipping paper, placards and labels, loading and unloading, driving and parking rules, emergency response, and the Emergency Response Guidebook (ERG).

The Iowa Department of Transportation Motor Vehicle Division follows the federal CDL standards established by FMCSA. To earn the Hazmat credential, you must answer at least 80% of the questions correctly. Many candidates score lower the first time because the test pulls from a large pool — refreshing this page will give you a different mix of questions, drawn from the same authoritative source.

Want more practice? Try the full Hazmat question bank or browse all Iowa CDL practice tests.