Which one of the following is a characteristic of non-flammable compressed gases?

Non-flammable compressed gases are defined by their inability to support combustion. This means that while they may be involved in various chemical processes or reactions, they do not provide a means for a fire to sustain or propagate. This characteristic is critical in ensuring safety during storage and handling, as the presence of non-flammable gases reduces the risk of fires and explosions associated with combustible materials.

In contrast, gases that ignite easily or support combustion would pose a significant safety risk in environments where flammable substances are present. The option suggesting that non-flammable gases might be lighter than air misrepresents their physical properties, as non-flammable gases can be either lighter or heavier than air, depending on their molecular composition. Understanding these traits is essential for safe handling and application of non-flammable compressed gases in various industrial and laboratory settings.