Natural gas composition check: identify the main constituent (principal component) of typical natural gas supplied by pipelines and fields.

Introduction:
Natural gas is an energy commodity composed primarily of light hydrocarbons. Recognizing its principal component is fundamental for combustion calculations, safety, and processing (e.g., sweetening, dehydration, NGL recovery).

Given Data / Assumptions:

• Pipelines and field gas compositions vary but share a dominant component.
• Minor constituents may include ethane, propane, nitrogen, CO2, and trace sulfur compounds.

Concept / Approach:
Methane (CH4) is the main component of natural gas, commonly above 85% by volume in sales gas, with ethane and heavier hydrocarbons present in smaller amounts. Acetylene (C2H2) and ethylene (C2H4) are not typical major constituents of natural gas streams.

Step-by-Step Solution:
List candidates and typical abundance.Identify methane as the overwhelmingly dominant hydrocarbon.Select CH4 as the correct answer.

Verification / Alternative check:
Gas specifications and custody transfer documents treat methane as the basis for energy content; NGL recovery plants remove some C2+ components, confirming methane dominance in pipeline-quality gas.

Why Other Options Are Wrong:
C2H6 (ethane): Common secondary component but not the main one.C2H4 (ethylene) / C2H2 (acetylene): Trace or absent in natural gas; associated with petrochemical production.CO: Impurity in some streams, not the principal component.

Common Pitfalls:
Confusing natural gas with LPG (C3–C4) or refinery fuel gases containing more olefins; natural gas is methane-rich.

Final Answer:
CH4