Which of the following statements about biogas production and methanogens is correct?

Biogas is a mixture of gases mainly containing CH₄, CO₂, and H₂, and is produced by methanogenic bacteria.

The correct answer is Option (1) Biogas is a mixture of gases mainly containing CH₄, CO₂, and H₂, and is produced by methanogenic bacteria.

Option 1: Biogas is a mixture of gases mainly containing CH₄, CO₂, and H₂, and is produced by methanogenic bacteria.

Biogas primarily comprises methane (CH₄), carbon dioxide (CO₂), and small amounts of other gases like hydrogen (H₂) and traces of hydrogen sulfide (H₂S).

Option 2 : Biogas is produced by aerobic bacteria that break down cellulosic material is wrong statement .

Methanogenic bacteria, specifically a group of anaerobic microorganisms called methanogens that grow on cellulosic material in the absence of oxygen, are responsible for producing methane during the anaerobic breakdown of organic matter in environments lacking oxygen, such as in biogas digesters. These bacteria play a vital role in the decomposition of organic material into biogas.

Option 3 : Methanogens are aerobic bacteria found in the dung of cattle is a wrong statement .

Biogas production occurs in biogas plants, which typically consist of a concrete tank where bio-wastes and a slurry of dung are collected. The methanogenic bacteria in the dung act on the biowaste to produce biogas, which is used for cooking and lighting in nearby houses. The biogas plant has an outlet connected to a pipe to supply the biogas.

Option 4: Biogas commonly called gobar gas, is pure methane is wrong statement because biogas primarily comprises methane (CH₄), carbon dioxide (CO₂), and small amounts of other gases like hydrogen (H₂) and traces of hydrogen sulfide (H₂S).

Therefore, the correct statement is (1) - Biogas is a mixture of gases mainly containing CH₄, CO₂, and H₂, and is produced by methanogenic bacteria.