Which one of the following statements regarding gases is incorrect?

The statement that methane is heavier than air is incorrect because methane actually has a lower density than air. Methane's molecular weight is about 16 g/mol, while the average molecular weight of air is approximately 29 g/mol. This means that methane is lighter than air, allowing it to rise and disperse more readily in the atmosphere.

Understanding the characteristics of gases is crucial for safety in confined spaces, as lighter-than-air gases can accumulate at high points, while heavier-than-air gases can settle in low areas, creating potential hazards such as asphyxiation or explosion. For example, both hydrogen sulfide and carbon monoxide, which are correctly described in the other statements, have important implications for workplace safety because of their density and toxic properties.