Hazmat CDL Test Prep: Study Guide & Key Topics
The hazmat knowledge test has 30 multiple-choice questions with an 80% passing score. You need 24 correct answers. This guide covers every major topic, study strategies, free resources, and the most common trick questions so you can pass on your first attempt.
30
Questions
80%
Passing Score
24
Correct Needed
1-2 Weeks
Study Time
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O TruckingHazmat CDL Test Prep: Study Guide & Practice Questions
Test Format & Rules
The hazmat knowledge test is administered at your state DMV after your TSA background check clears. For the complete application process, see our how to get a hazmat endorsement guide.
Format
- 30 multiple-choice questions
- 4 answer options per question
- No time limit (but most finish in 30-45 min)
- Computer-based at most DMV locations
Passing Requirements
- 80% passing score = 24 out of 30 correct
- You can miss up to 6 questions
- Retakes available after waiting period
- Retake fee varies by state ($5-$25)
Hazardous Materials Table (49 CFR 172.101)
The Hazardous Materials Table is the most tested topic. You do not need to memorize the entire table, but you must understand its structure and how to look up information:
| Column | Information | What It Tells You |
|---|---|---|
| 1 | Symbols | Special provisions (+ means more than one name) |
| 2 | Proper Shipping Name | The official name to use on shipping papers |
| 3 | Hazard Class/Division | The category of hazard (1-9) |
| 4 | ID Number | UN or NA number for the material |
| 5 | Packing Group | Danger level (I=great, II=medium, III=minor) |
| 6 | Labels | Required labels for packages |
| 7 | Special Provisions | Special rules for this material |
| 8 | Packaging | Authorized packaging types |
| 9 | Quantity Limits | Max quantities for aircraft transport |
The 9 Hazard Classes
Know these classes and their divisions — test questions frequently ask you to identify the correct class:
Class 1
Explosives (1.1 through 1.6)
Class 2
Gases (2.1 flammable, 2.2 non-flammable, 2.3 toxic)
Class 3
Flammable Liquids
Class 4
Flammable Solids (4.1, 4.2 spontaneous, 4.3 water-reactive)
Class 5
Oxidizers (5.1) & Organic Peroxides (5.2)
Class 6
Toxic (6.1) & Infectious (6.2)
Class 7
Radioactive Materials
Class 8
Corrosives
Class 9
Miscellaneous (lithium batteries, dry ice, etc.)
Placarding Rules
Heavily tested topic. Key rules to know:
Table 1 materials (explosives, poison gas, water-reactive) — placard required for ANY quantity
Table 2 materials — placard required when shipping 1,001 lbs or more (aggregate gross weight)
Placement: front, rear, and both sides of the vehicle — 4 placards total
DANGEROUS placard: can be used when carrying two or more Table 2 materials (1,001+ lbs each)
Loading & Unloading Procedures
Key rules the test covers include:
Never smoke within 25 feet of a placarded vehicle
Set the parking brake and chock wheels before loading
Turn engine off during loading of most hazmat (except when needed to run a pump)
Never load incompatible materials together (oxidizers + flammables, acids + cyanides)
Secure all packages to prevent movement during transit
Emergency Response
Emergency procedures tested include:
The Emergency Response Guidebook (ERG) must be carried on the vehicle
In case of a spill or leak: secure the area, warn others, do not walk through or touch the material
Call 911 and CHEMTREC (1-800-424-9300) for emergency assistance
Keep shipping papers accessible so responders can identify the material quickly
Shipping Papers
Every hazmat shipment must have shipping papers listing:
- Proper shipping name — from the Hazardous Materials Table (Column 2)
- Hazard class or division — from Column 3
- UN/NA identification number — from Column 4
- Packing group — from Column 5 (when applicable)
- Total quantity — weight or volume of the hazmat
- Emergency response phone number — accessible 24/7
The driver must keep shipping papers within reach while driving (in the door pouch or on the seat) and on the dashboard or driver's seat when outside the vehicle. This allows emergency responders to quickly identify the hazardous materials if the driver is incapacitated.
Common Trick Questions
Q: When is the DANGEROUS placard used?
Trick: Only for Table 2 materials. Table 1 materials ALWAYS require their specific hazard class placard, never the generic DANGEROUS placard.
Q: Where should shipping papers be when driver leaves the cab?
Trick: On the driver's seat or in a holder mounted on the driver's door. NOT in the glove box or under the seat.
Q: What is the minimum distance for smoking near a placarded vehicle?
Trick: 25 feet. Not 50 feet (that is for parking near an open fire). Not 10 feet. 25 feet is the smoking rule.
Q: Who is responsible for placarding the vehicle?
Trick: The shipper provides placards, but the DRIVER is responsible for ensuring they are properly displayed before moving the vehicle.
Study Plan & Free Resources
Your state CDL manual (hazmat section): The primary study source. Available free from your state DMV website as a PDF download.
Online practice tests: Sites like CDL Test Prep, Cristcdl.com, and DMV-Written-Test.com offer free hazmat practice tests that closely mirror actual exam questions.
Mobile apps: CDL Prep (iOS/Android) offers offline study with hazmat-specific question banks. Most are free with optional premium features.
Recommended study time: 1-2 weeks, 30-60 minutes per day. Focus on the hazmat table, placarding rules, and emergency procedures — these make up the majority of test questions.
Take Practice Tests Until You Score 90%+
Test Day Tips
Arrive 15 minutes early with your CDL, TSA approval letter, and payment
Read each question completely before looking at the answer options
Watch for absolute words like "never" and "always" — they are often in wrong answers
If unsure, eliminate obviously wrong answers first, then choose the safest-sounding option
Consider taking the tanker test the same day for the X endorsement
How Our Team Supports Your Hazmat Career
We dispatch hazmat loads as soon as you pass
At O Trucking LLC, once your H endorsement is active, we immediately start matching you with premium hazmat freight. See our hazmat pay guide for what you can expect to earn.
Pass the Test, Start Earning More
Our dispatch team is ready to book premium hazmat loads for you the moment your endorsement is active. Study hard, pass once, and start earning 15-25% more per load.