Which statement best describes the situations in which chemical reactivity hazards can occur?

• A. When processing conditions exceed normal operating conditions
• B. When storing or transporting chemicals
• C. All of the above
• D. When chemicals are accidentally mixed together

Answer: (C)

Reactivity hazards show up whenever a chemical can react in an undesired and potentially dangerous way, which can happen in several ways. If processing conditions stray outside what’s safe, temperatures or pressures can drive an exothermic reaction or even a runaway reaction, leading to heat release, pressure buildup, fires, or explosions. In storage or during transport, chemicals may encounter conditions (such as heat, moisture, contamination, or incompatible surroundings) that destabilize them or promote dangerous reactions, including formation of gases or peroxides, or container failures. And if chemicals are accidentally mixed, especially incompatible substances, vigorous or violent reactions can occur because the reactive components come together in the wrong place or at the wrong time.

All of these situations describe legitimate pathways for reactivity hazards, so the best choice is the one that includes all of them. Each scenario highlights a common way reactive hazards can arise in real settings, and recognizing that broadened view helps in designing effective controls across processing, storage, and handling.