What does Division 1.1 of Class 1 signify?

Division 1.1 of Class 1 signifies explosives that pose mass explosion hazards. This classification is critical because it identifies substances that, if detonated, can produce a massive and instantaneous release of energy capable of causing destruction over a wide area. Mass explosions are particularly dangerous due to their potential to affect multiple individuals and significant property damage, which is why regulations surrounding these materials are stringent.

This classification is part of the broader system of categorizing hazardous materials based on their risks. Having a clear understanding of Division 1.1 allows emergency responders and safety personnel to take appropriate precautions and responses when dealing with such materials to safeguard lives and property. In contrast, the other answer choices relate to different types of hazards that do not involve mass explosion risks. For instance, gases under pressure and flammable solids have their own classifications that address different safety concerns, but they do not correspond to the threats posed by mass explosion hazards outlined in Division 1.1.