Which of the following is an example of a Class 2 gas other than acetylene?

• A. Dynamite
• B. Water vapor
• C. Anhydrous Ammonia
• D. Oxygen

Answer: (C)

Class 2 gases are gases and include several hazard types: flammable gases, non-flammable gases, and toxic gases. The idea is to match a gas to its hazard category within this class. Acetylene is a well-known flammable gas, so the question is asking for another gas that fits into Class 2 but is not acetylene.

Anhydrous Ammonia fits here because it is a toxic gas. It can cause serious respiratory and mucous membrane irritation and can be hazardous even at relatively low concentrations, which is why it’s classified as a toxic gas (2.3) within Class 2. In contrast, water vapor isn’t typically treated as a regulated Class 2 gas in many training contexts, and oxygen, while non-flammable and essential for combustion, is categorized as a non-flammable gas (2.2) rather than a toxic one. Dynamite is a solid explosive, not a gas, so it wouldn’t be placed in Class 2 gases.