Chemical properties of hazardous materials primarily inform responders about how those chemicals will:

The chemical properties of hazardous materials are crucial for responders because they provide vital information about how those chemicals will react under various conditions. Understanding the reactivity of a substance helps responders anticipate potential hazards during an incident, such as the risk of explosions, gas releases, or the formation of corrosive by-products when the material interacts with other substances or environmental factors.

This knowledge allows responders to make informed decisions about the safest approach to mitigate risks, control spills, or conduct firefighting operations. For example, knowing that a chemical is highly reactive with water could prevent a responder from using water to extinguish a fire involving that chemical, thereby avoiding further danger.

In contrast, the other choices pertain to different aspects that, while relevant, do not directly inform a responder about the most critical immediate risk during an emergency situation. Understanding how a substance is transported involves logistics and regulations rather than reaction properties, degradation deals more with the breakdown of materials over time rather than immediate hazard assessment, and concentration relates to the amount of the substance rather than its chemical behavior. Therefore, focusing on reactivity is essential for effective hazard management and emergency response.