The statement 'Carbon dioxide is a noncombustible gas that is lighter than air' is:

The statement 'Carbon dioxide is a noncombustible gas that is lighter than air' is:

• A. True
• B. Neither
• C. False
• D. Both

Answer: (C)

Understanding how gases behave in fires is key. Carbon dioxide does not support combustion, which is the part that’s true. But it is heavier than air, not lighter. At room conditions its density is about 1.8 kg/m³ (air is about 1.2 kg/m³), so CO2 tends to stay low and pool in basements and low-lying areas, displacing oxygen. Because of that, the statement claiming it is lighter than air is incorrect. The overall assessment is that the statement is false.

Understanding how gases behave in fires is key. Carbon dioxide does not support combustion, which is the part that’s true. But it is heavier than air, not lighter. At room conditions its density is about 1.8 kg/m³ (air is about 1.2 kg/m³), so CO2 tends to stay low and pool in basements and low-lying areas, displacing oxygen. Because of that, the statement claiming it is lighter than air is incorrect. The overall assessment is that the statement is false.