Question

The chief constituent of biogas is _____.

Answer 1

Hint: Biogas is a gas produced by breakdown of organic compounds so mostly it will contain a gas which is an organic compound.

Complete step by step answer:
Biogas is formed due to the anaerobic (in the absence of oxygen) breakdown of organic matter. Biogas can be formed from agricultural waste, manure, municipal waste, plant waste, sewage etc…. The anaerobic breakdown or digestion takes place in closed systems called anaerobic digester, bio digester or otherwise called a bioreactor. Biogas is primarily made up of methane and carbon dioxide with a small amount of hydrogen sulphide, siloxanes and moisture.
Methane $\text{(C}{{\text{H}}_{\text{4}}}\text{)}$ constitutes 50-75 percentage of biogas, while carbon dioxide takes up 25-50 percentage, so we can say that methane is the major constituent of biogas.
So the answer to the question is Methane.

Additional Information:
Biogas can be compressed after removal of Carbon dioxide, the same way as natural gas is compressed to CNG, and used to power motor vehicles.
Biogas can be cleaned and upgraded to natural gas standards, when it becomes bio-methane. Biogas is considered to be a renewable resource because its production-and-use cycle is continuous, and it generates no net carbon dioxide.

Note: Biogas is produced by microorganisms, such as methanogens and sulfate-reducing bacteria, performing anaerobic respiration.
Biogas can be produced both naturally and industrially. Methane producing areas like wetlands, oceans, forest soil etc… Industrially biogas is produced for fuel. Biogas is produced as landfill gas, which is produced by the breakdown of biodegradable waste inside a landfill or as digested gas which is produced inside an anaerobic digester.