Commander Examination Practice

Illinois Hazardous Materials Incident Commander Examination Practice Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• Which element of the Incident Command System (ICS) is primarily

responsible for developing the Incident Action Plan (IAP)?

• Operations Section Chief
• Planning Section Chief
• Logistics Section Chief
• Incident Commander

Rationale: The Incident Commander has overall responsibility for

developing and approving the IAP, setting objectives and priorities; section chiefs provide input and implement components.

• On arrival at a hazmat scene, the first priority for the Incident

Commander is:

• Scene perimeter restoration 1 / 4

• Life safety
• Property protection
• Environmental monitoring

Rationale: Life safety (rescue and protection of responders and

public) takes precedence over property and environment in the incident priorities.

• Which resource provides initial isolation and protective action

distances for unpressurized spills of liquids and gases?

A. NFPA 704

• Emergency Response Guidebook (ERG)
• Material Safety Data Sheet (MSDS)
• OSHA Hazard Communication Standard

Rationale: The ERG gives first-responder guidance for initial

isolation/protective actions for transportation incidents before detailed information is available.

4. A material with a vapor density of 3.5 will:

• Rise and disperse rapidly in air
• Remain at ceiling level
• Sink and accumulate in low areas
• Behave neutrally with air

Rationale: Vapor density >1 means vapors are heavier than air and

will tend to collect in low spots, basements, and confined spaces. 2 / 4

• Which personal protective equipment (PPE) ensemble provides the

highest level of respiratory and skin protection against unknown chemical exposures?

• Level B
• Level A
• Level C
• Level D

Rationale: Level A provides fully encapsulating chemical-resistant suit

with SCBA, offering maximum skin and respiratory protection for unknown or highly hazardous atmospheres.

6. The term IDLH refers to:

• Immediate Dangerous to Life and Health concentration
• Index of Dangerous Loss of Health
• Immediately Dangerous to Life or Health
• Inhalation Dose Limit Hazard

Rationale: IDLH is the OSHA/NIOSH term indicating an atmosphere

posing an immediate threat to life or health or that would impair escape.

• When establishing the hot, warm, and cold zones, which zone is the

decontamination corridor normally located in?

• Hot zone
• Warm zone
• Cold zone 3 / 4

• Control zone

Rationale: The warm zone is the transition area where

decontamination occurs between the hot (contaminated) and cold (support/command) zones.

• Which placard background color indicates a flammable gas under the

DOT placard system?

• White
• Red
• Red with flame symbol (flammable)
• Yellow

Rationale: DOT placards for flammable gases use red (flammable)

with appropriate hazard class numbers and symbols; specifics vary by class but red indicates flammability.

9. A product with a flash point below 23°C (73°F) is classified as:

• Combustible liquid
• Flammable liquid
• Oxidizer
• Corrosive

Rationale: Flash point <23°C classifies a liquid as flammable (per

many regulatory schemes, e.g., NFPA/DOT definitions).

• The best method to identify an unknown solid substance found

at a scene when labels are missing is to:

• Smell the substance carefully
• / 4