Ace the ACS Lab Crash Course 2025 – Safety Savvy Awaits!

The characteristic of being highly flammable or igniting easily is a direct indication of a chemical's potential hazards related to combustion. Chemicals that are termed "flammable" typically have low flash points, meaning they can vaporize and catch fire at relatively low temperatures. This makes them particularly dangerous in environments where ignition sources may be present, such as open flames, sparks, or even static electricity.

In laboratories, recognizing this intrinsic property is crucial for safety protocols. It prompts the need for proper storage, handling, and disposal methods to mitigate risks associated with fire hazards. For instance, flammable chemicals should be stored in appropriate containers, away from heat sources, and under specified safety regulations to prevent accidents.

The other options, while they might relate to properties or considerations regarding chemicals, do not specifically indicate flammability. A strong odor could be associated with many substances, including those that are non-flammable. Stored in an opaque container does not inherently suggest flammability, and a high boiling point usually indicates a lower volatility, which is often correlated with reduced flammability. Thus, recognizing that a chemical is highly flammable or ignites easily is the most direct and relevant indication of its fire-related hazards.