Which statement is true regarding natural gas?

Natural gas is primarily composed of methane (CH4), which has a lower density than air. This characteristic means that when released, natural gas will rise and disperse into the atmosphere rather than settling to the ground. Being lighter than air is an important quality since it influences how natural gas behaves in the event of a leak and dictates safety measures that need to be in place.

The other statements do not accurately reflect the properties of natural gas. For instance, natural gas is indeed combustible when mixed with an appropriate amount of oxygen, which is essential for combustion. Additionally, it does require oxygen to burn, negating the assertion that it requires no oxygen for combustion. Lastly, being lighter than air relates to how it behaves in the environment, contrasting with the false notion that it is heavier. Understanding these properties is crucial for ensuring safe handling and usage of natural gas in HVACR systems.