What hazard is associated with propane gas when heaters are installed in enclosed areas?

The correct answer identifies propane gas as heavier than air. Understanding this property is crucial for safety in installations where propane heaters are used, especially in enclosed areas.

When propane is released, it tends to accumulate in lower areas due to its density being greater than that of air. This can create a significant hazard as it may lead to the formation of flammable mixtures at ground level, where ignition sources may be present. Therefore, proper ventilation is essential in any space where propane is used to ensure that any leaked gas dissipates instead of pooling, which could result in dangerous situations, including explosions or fire.

In contrast, the other options do not align with the physical characteristics of propane or the related hazards. For instance, propane is not inert, meaning it can react with air and produce flammable mixtures, and it is not odorless either; it is often mixed with a substance called ethyl mercaptan that gives it a distinctive smell to help in detecting leaks. Thus, understanding that propane gas is heavier than air is vital for implementing safety measures in environments where it is used.