Natural gas is mostly made up of?

Natural gas is primarily composed of methane, which is the main hydrocarbon being around 70-90% of natural gas by volume. Ethane is also present but in smaller quantities, typically around 5-15%. The composition can vary based on the source of the natural gas, but methane remains the dominant component.

Methane (CH4) is a simple molecule, consisting of one carbon atom and four hydrogen atoms, making it the lightest and most abundant alkane in natural gas. Ethane (C2H6), while also an alkane, consists of two carbon atoms and six hydrogen atoms, contributing to the gas's overall energy content but in lesser amounts compared to methane.

The other options containing combinations of butane and propane do not accurately represent the typical composition of natural gas, as these compounds are heavier hydrocarbons and are usually separated out during the processing of natural gas for distribution and consumption. Therefore, the choice that accurately reflects the main components of natural gas is the one identifying methane and ethane.