North Carolina CDL — General Knowledge practice
North Carolina CDL — General Knowledge: Alcohol & Drugs practice test
Blood alcohol limits, zero-tolerance and implied-consent laws, and how alcohol and drugs — legal or not — affect your driving.
Content reviewed against official driver handbooks · August 12, 2026
12 questions · pass with 10 correct. You get instant feedback and an explanation after every answer.
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12 sample Alcohol & Drugs questions with the correct answer, a short explanation, and the official handbook reference. Read through them, then take the quiz above.
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1. How does alcohol affect a driver's abilities?
Correct answer: It impairs coordination, reaction time, and judgment
Alcohol dulls coordination, slows reaction time, and weakens depth perception and night vision, while clouding the judgment that safe driving requires.
Source: North Carolina CDL Driver Handbook — Section 2: Driving Safely (2.22.1)
2. About how fast can the liver process alcohol?
Correct answer: About one-third of an ounce of alcohol per hour
The liver can process only about one-third of an ounce of alcohol per hour — less than a standard drink — and only time will sober you up.
Source: North Carolina CDL Driver Handbook — Section 2: Driving Safely (2.22.1)
3. Under the rules, which over-the-counter medicines can be a problem for a commercial driver?
Correct answer: Common cold medicines that can cause drowsiness
Cold medicines and similar over-the-counter drugs can make a driver drowsy and impair safe driving, so drivers must pay attention to warning labels.
Source: North Carolina CDL Driver Handbook — Section 2: Driving Safely (2.22.2)
4. At what blood alcohol concentration does it become illegal to operate a commercial motor vehicle?
Correct answer: .04 percent
It is illegal to drive a CMV with a blood alcohol concentration of .04 percent or more — a lower limit than for non-commercial drivers.
Source: North Carolina CDL Driver Handbook — Section 1: Introduction (1.3.2)
5. Which of these contains about the same amount of alcohol as a 1.5-ounce shot of 80-proof liquor?
Correct answer: A 12-ounce glass of ordinary beer
A regular 12-ounce beer, a 5-ounce serving of wine, and a single 1.5-ounce shot of 80-proof liquor each hold about the same amount of alcohol.
Source: North Carolina CDL Driver Handbook — Section 2: Driving Safely (2.22.1)
6. If a first alcohol offense occurs while you are driving a CMV placarded for hazardous materials, how long will you lose your CDL?
Correct answer: Three years
The disqualification is at least three years if the offense happens while operating a vehicle placarded for hazardous materials, rather than the usual one year.
Source: North Carolina CDL Driver Handbook — Section 1: Introduction (1.3.2)
7. What is the penalty for a second major alcohol- or drug-related offense involving a CMV?
Correct answer: Loss of the CDL for life
A second major offense of this kind means losing the CDL permanently; the same lifetime loss applies to anyone who uses a commercial vehicle in a felony tied to controlled substances.
Source: North Carolina CDL Driver Handbook — Section 1: Introduction (1.3.2)
8. For at least how long do you lose your CDL the first time you refuse a required alcohol test while operating a CMV?
Correct answer: At least one year
Refusing to undergo blood alcohol testing while operating a CMV results in loss of your CDL for at least one year on a first offense.
Source: North Carolina CDL Driver Handbook — Section 1: Introduction (1.3.2)
9. Which method will actually reduce a person's blood alcohol concentration?
Correct answer: Letting enough time pass
Only the passage of time lowers BAC; black coffee, a cold shower, or fresh air do not speed up how fast the body removes alcohol.
Source: North Carolina CDL Driver Handbook — Section 2: Driving Safely (2.22.1)
10. What happens if you are found operating a CMV with a detectable amount of alcohol below .04 percent?
Correct answer: You are placed out of service for 24 hours
Any detectable amount of alcohol under .04 percent puts you out of service for 24 hours.
Source: North Carolina CDL Driver Handbook — Section 1: Introduction (1.3.2)
11. Which part of the brain does alcohol affect first as blood alcohol concentration rises?
Correct answer: The part controlling judgment and self-control
Alcohol first affects the part of the brain that controls judgment and self-control, which is dangerous because it can keep drinkers from realizing they are impaired.
Source: North Carolina CDL Driver Handbook — Section 2: Driving Safely (2.22.1)
12. When is it permitted to drive after taking a prescription drug?
Correct answer: Only if the doctor says it will not affect safe driving
You may drive after taking a drug prescribed by a doctor only if the doctor has told you it will not affect your ability to drive safely.
Source: North Carolina CDL Driver Handbook — Section 2: Driving Safely (2.22.2)
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Every North Carolina question is written from the official North Carolina driver handbook and checked against its current edition. DMV Test Free is a free, independent study resource — not affiliated with any DMV or government agency. About DMV Test Free