In the composition of natural gas used as a fuel, which component is present as the primary or major constituent?

Introduction / Context:
Natural gas is an important fossil fuel widely used for cooking, heating and power generation. It is considered cleaner than many other fossil fuels because it produces less carbon dioxide per unit of energy. To understand its properties and uses, it is useful to know the major chemical component of natural gas. This question checks whether you know which hydrocarbon forms the largest fraction of natural gas in typical commercial supplies.

Given Data / Assumptions:

• Natural gas is a mixture of light hydrocarbons and small amounts of other gases.
• The most important components are methane, ethane, propane and small amounts of higher hydrocarbons.
• There may also be trace amounts of nitrogen, carbon dioxide and other impurities.
• The question asks specifically for the primary or major constituent.

Concept / Approach:
Chemistry textbooks consistently describe methane as the main component of natural gas, usually accounting for more than 80 percent of the mixture. Other hydrocarbons such as ethane and propane are present in smaller amounts and may be separated for use as liquefied petroleum gas. Therefore, when asked for the primary component of natural gas, the correct answer is methane. Recognising this is important when studying combustion reactions, calorific values and environmental impacts of fuel use.

Step-by-Step Solution:
Step 1: Recall that natural gas is a fossil fuel mainly made up of light hydrocarbons. Step 2: Remember that methane is the simplest hydrocarbon with one carbon atom and four hydrogen atoms. Step 3: Note that typical natural gas compositions list methane as the majority component by volume. Step 4: Compare this with ethane and propane, which are present only in smaller percentages. Step 5: Select methane from the options as the primary component of natural gas.

Verification / Alternative check:
You can verify this by considering how natural gas is processed. In gas processing plants, methane is often left as pipeline gas, while other hydrocarbons such as propane and butane are extracted and sold as liquefied petroleum gas. This industrial practice reflects the fact that methane dominates the mixture. Also, combustion equations for natural gas are commonly written using methane as the representative fuel, which confirms its primary role in the mixture.

Why Other Options Are Wrong:
Ethane and propane are important minor components but they do not form the bulk of natural gas under normal conditions.
Nitrogen and carbon dioxide are usually present only as impurities or in very small amounts and do not provide fuel value.
Any gas that is not the main hydrocarbon in the mixture cannot be considered the primary constituent of natural gas.

Common Pitfalls:
Some students confuse natural gas with liquefied petroleum gas and may think propane or butane is the major component. Another mistake is to assume that nitrogen is primary because air contains a large amount of nitrogen, but natural gas is a separate fuel mixture. Always remember that natural gas is mainly methane, while liquefied petroleum gas contains a higher proportion of propane and butane.

Final Answer:
The major constituent and primary component of natural gas is methane.