What does an increase in specific gravity indicate about a gas?

An increase in specific gravity indicates that a gas is heavier than air. Specific gravity is a measure that compares the density of a gas to the density of air. If the specific gravity of a gas is greater than 1, it is denser than air, meaning it will tend to sink and accumulate in low-lying areas. This is an important consideration in safety and handling practices, as heavier-than-air gases can pose risks of accumulation and potential hazards in confined spaces.

Understanding specific gravity in this context is crucial for individuals working with gases, as it influences ventilation requirements and emergency response strategies. In contrast, gases with a specific gravity less than 1 are lighter than air and will rise. The other options regarding flammability and heating value do not directly relate to specific gravity and thus do not apply in this context.