Which of the following is NOT a form of chemical agent?

• A. Vapors
• B. Dust
• C. Solids
• D. Gases

Answer: (B)

Chemical agents are spread in ways that allow them to travel through air and reach a target, most efficiently as vapors or gases because they mix with air and disperse quickly. A solid particulate like dust isn’t a typical form that a chemical agent itself takes for dissemination; it’s a solid particle that could carry contaminants but isn’t recognized as a chemical agent form on its own. While some agents can appear as powders in certain contexts, the standard form used for chemical agents in most settings is not dust. So, dust is the correct choice since it is not a form of chemical agent.