Home › Practice › General Knowledge › Question 46

General Knowledge Practice Question 46

RequiredGeneral Knowledge · Question 46

A standard DOT drug screen tests for how many substances?

• A3
• B5
• C10
• D15

Correct answer: B. 5

Why: The DOT 5-panel screen covers marijuana, cocaine, opiates (including semi-synthetic), amphetamines (including methamphetamine and MDMA), and phencyclidine (PCP).

How this question fits the General test

FMCSA requires General Knowledge competency under 49 CFR 383.111 because every CDL holder operates a heavy vehicle in mixed traffic where situational judgment, pre-trip discipline, and emergency response routinely separate a safe trip from a fatal one.

Study technique for this topic

Read the FMCSA Model CDL Manual Section 2 cover to cover, then re-read it focused on numbers — speeds, distances, weights, and pressures. Use the practice questions in this category to drill those numeric thresholds until you can answer without hesitation.

Related General practice questions

• Q26. Vehicles always required to stop at every railroad crossing include:
• Q39. When descending a long downgrade you should:
• Q53. Reflective triangles after a stop on the road must be set out within:
• Q1. What is the most frequent cause of crashes involving commercial motor vehicles?
• Q14. Total stopping distance equals:

Continue your CDL preparation

The General Knowledge portion of the CDL knowledge exam covers more than this single question. Use this site's full General Knowledge bank to drill every topic, then test yourself with one of our state-specific practice sets to confirm you are ready for the actual DMV exam in your state. Always check your state's CDL handbook for any local addenda before the test day.

If you are still building your overall CDL foundation, start with the General Knowledge bank — every CDL applicant must pass it — and then work outward to the endorsements you plan to add.