What substance is found in smaller amounts alongside methane in natural gas?

Natural gas primarily consists of methane, which is the main component. However, it also contains other hydrocarbons in smaller amounts, and ethane is one of those significant components. Ethane is a two-carbon alkane and typically accompanies methane in the natural gas mixture due to their similar formation processes in natural geological environments.

While propane and butane can be present in natural gas, they are usually found in higher concentrations in LPG (liquefied petroleum gas) rather than in natural gas itself. Hexane, which is a longer-chain alkane, is generally not a component of natural gas, as it would typically be found in heavier hydrocarbons and not in the lighter gases associated with natural gas. This makes ethane the correct answer, as it is the hydrocarbon most commonly present in smaller amounts alongside methane in natural gas.