Which of the following materials would be classified as Class 9 (Miscellaneous Hazardous Materials)?

• A. Molten sulfur
• B. Gasoline
• C. PCBs
• D. Ammonia

Answer: (C)

Class 9 covers miscellaneous hazardous materials—hazards that don’t fit neatly into the other classes like flammable liquids, toxic gases, or corrosives. Materials in this category are often environmental hazards or have specialty risks that aren’t defined by the standard class labels. PCBs are a classic example because their main concern is environmental harm: they’re highly toxic and persistent, and their transport risk is framed around environmental contamination rather than flammability or acute toxicity. The other options fit other classes: gasoline is a flammable liquid (Class 3), ammonia is a toxic gas (Class 2), and molten sulfur would be categorized by its specific hazard profile rather than as a miscellaneous environmental hazard. So PCBs belong in Class 9.