Is CNG considered lighter than air?

When considering whether CNG (Compressed Natural Gas) is lighter than air, it's important to understand the composition of CNG, which primarily consists of methane (CH4). Methane has a lower density than the average density of air. Under standard atmospheric conditions, this means that CNG will rise if released into the atmosphere because it is indeed lighter than air.

This property is crucial for safety when handling CNG, as it dissipates quickly when released, minimizing the risk of accumulation and potential hazards associated with flammable gases. Therefore, stating that CNG is considered lighter than air is correct, affirming that its physical properties influence its behavior in various situations, especially in terms of safety considerations.

The other options introduce conditions or variables that aren't necessary for a clear understanding of CNG’s general characteristics as it relates to air density.