Common characteristics of gases: Which is NOT a characteristic?

• A. Flammable
• B. Nonflammable
• C. Toxic
• D. Inert

Answer: (D)

The main idea here is how gases are typically described in terms of hazards. Gases are often discussed by characteristics that apply to many of them, such as being flammable or toxic, or being nonflammable. Inert means chemically nonreactive, which is not a property that applies to most gases in a general sense. While there are inert gases (like helium, neon, argon), inertness isn’t a common or defining feature for the majority of gases you encounter. Most hazardous gases you deal with are either flammable, toxic, or reactive in some way, so inert isn’t a broad, typical characteristic. That’s why inert is the best choice for “not a common characteristic.”