Mississippi CDL — General Knowledge practice
Mississippi 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
14 questions · pass with 11 correct. You get instant feedback and an explanation after every answer.
Study questions with answers
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.
Show all 12 questions with answers
1. Why should you avoid drugs that mask fatigue?
Correct answer: Rest is the only cure for fatigue
Stimulants may keep you awake for a while, but they won't make you alert, and the tiredness returns. The only fix for fatigue is rest.
Source: Mississippi CDL Manual — Section 2: Driving Safely (Alcohol, Other Drugs, and Driving)
2. A CMV driver is found with a detectable amount of alcohol that is below 0.04%. What happens?
Correct answer: The driver is put out of service for 24 hours
Any detectable alcohol under .04% puts a CMV driver out of service for 24 hours.
Source: Mississippi CDL Manual — Section 1: Introduction (CDL Disqualifications)
3. When may a driver on duty use a drug prescribed by a doctor?
Correct answer: When the doctor says it will not affect the ability to drive safely
A prescribed drug is allowed when the prescribing doctor tells the driver it won't impair safe driving. Read warning labels and follow the doctor's orders.
Source: Mississippi CDL Manual — Section 2: Driving Safely (Alcohol, Other Drugs, and Driving)
4. When should you be especially watchful for drunk drivers?
Correct answer: Around the closing times of bars and taverns
Look for drivers who can't stay in their lane or hold a steady speed, or who stop for no reason.
Source: Mississippi CDL Manual — Section 2: Driving Safely (Roadway Factors)
5. A CDL holder's personal driving privilege is suspended for an alcohol violation in a private car. What happens to the CDL?
Correct answer: It is lost for one year
Losing your personal driving privilege for alcohol, controlled-substance, or felony violations costs you the CDL for a year, and no hardship license is available for CMV driving.
Source: Mississippi CDL Manual — Section 1: Introduction (Traffic Violations in Your Personal Vehicle)
6. At what blood alcohol concentration (BAC) does it become illegal to operate a commercial motor vehicle?
Correct answer: 0.04% or higher
For CMV drivers the limit is .04%. A first offense at that level brings at least a one-year CDL loss.
Source: Mississippi CDL Manual — Section 1: Introduction (CDL Disqualifications)
7. Alcohol first affects the part of the brain that controls judgment and self-control. Why is that especially dangerous?
Correct answer: It can keep drinkers from realizing they are getting drunk
As BAC rises, muscle control, vision, and coordination are affected too — but the loss of judgment comes first and hides the problem.
Source: Mississippi CDL Manual — Section 2: Driving Safely (Alcohol, Other Drugs, and Driving)
8. By operating a commercial motor vehicle, what are you considered to have agreed to?
Correct answer: Being tested for alcohol
Anyone who operates a CMV is deemed to have consented to alcohol testing. Refusing a test is treated like a major offense.
Source: Mississippi CDL Manual — Section 1: Introduction (CDL Disqualifications)
9. Which three factors determine your blood alcohol concentration?
Correct answer: How much you drink, how fast you drink it, and your body weight
More alcohol and faster drinking raise BAC, and a smaller person reaches a given BAC with less to drink.
Source: Mississippi CDL Manual — Section 2: Driving Safely (Alcohol, Other Drugs, and Driving)
10. A driver commits a first alcohol offense while operating a CMV placarded for hazardous materials. What is the minimum disqualification?
Correct answer: Three years
The usual one-year minimum rises to three years when the vehicle is placarded for hazmat. A second offense brings a lifetime loss.
Source: Mississippi CDL Manual — Section 1: Introduction (CDL Disqualifications)
11. Which group of drinks contains about the same amount of alcohol per serving?
Correct answer: 12 oz of 5% beer, 5 oz of 12% wine, and a 1.5 oz shot of 80-proof liquor
It is the alcohol, not the type of drink, that matters. Each of these standard servings holds roughly the same amount.
Source: Mississippi CDL Manual — Section 2: Driving Safely (Alcohol, Other Drugs, and Driving)
12. The liver removes alcohol at a fixed rate of about how much per hour?
Correct answer: One-third of an ounce
A standard drink holds more alcohol than that, and nothing speeds the rate up. If you drink faster than the liver clears alcohol, your BAC climbs.
Source: Mississippi CDL Manual — Section 2: Driving Safely (Alcohol, Other Drugs, and Driving)
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