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TEXAS DPS · WRITTEN TEST (CLASS C)

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Alcohol, drugs and DUI: Texas DPS written test practice

Rules to understand before practicing

Alcohol, some prescription drugs and other substances can impair attention, judgment and reaction time. A legal BAC threshold is not a promise that driving below it is safe. Age-specific, commercial-driver and chemical-test rules need the handbook for the state where you will test. A common mistake is expecting coffee, a shower or fresh air to remove alcohol impairment. Plan a sober ride before drinking, and check medicine warnings before driving.

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Start free practice

5 free practice questions on alcohol, drugs and DUI for the Texas DPS written knowledge test, each with the correct answer and a short explanation. Study them here, then check yourself in the interactive quiz or the exam simulator.

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About the Texas written test

30questions on the real test
21 / 30correct answers to pass (70%)
3attempts allowed within 90 days

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1. For drivers 21 years of age and older, driving with a blood alcohol concentration (BAC) is considered illegal starting at:

  1. 0.05%
  2. ✓ 0.08%
  3. 0.10%
  4. Any detectable amount

Explanation: 0.08% — the legal limit for drivers aged 21 and older.

Official reading · set1-018

2. Texas's "zero tolerance" law sets the illegal BAC for drivers under the age of 21 at:

  1. 0.08%
  2. 0.05%
  3. ✓ Any detectable amount (0.00%)
  4. 0.02%

Explanation: Texas has a true zero-tolerance policy for drivers under 21—any detectable amount of alcohol in their system is a violation, under the Texas Alcoholic Beverage Code.

Official reading · set1-019

3. A commercial vehicle driver is considered to be intoxicated if their BAC is:

  1. 0.08%
  2. ✓ 0.04% and higher
  3. 0.02%
  4. 0.10%

Explanation: For commercial drivers, a stricter limit applies—0.04%.

Official reading · set1-020

4. The "implied consent" law in Texas means:

  1. You can decline the chemical test without any consequences
  2. ✓ By driving a car, you have already agreed to take a chemical test if you are lawfully arrested for a DUI
  3. It applies only to drivers who are 21 or older
  4. It is used only after a traffic accident

Explanation: Refusing a chemical test following a lawful arrest for DUI/DWI automatically results in a license suspension in Texas—separate from any potential DUI charge.

Official reading · set1-021

5. Drivers and passengers are prohibited from having the following items inside the vehicle:

  1. Food or drinks
  2. ✓ An open container of alcohol
  3. Phone Holder
  4. Sunglasses

Explanation: Open containers of alcohol are prohibited inside the vehicle for both the driver and passengers.

Official reading · set1-022

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Content updated October 4, 2026 · How we review content