The decomposition which takes place in the absence of oxygen is called anaerobic degradation. Anaerobic degradation is carried out by the micro-organisms called anaerobic bacteria. Biogas is a mixture of methane, carbon dioxide, hydrogen and hydrogen sulphide. The major constituent of biogas is methane.1. The decomposition which takes place in the absence of oxygen is calleda. Anaerobic degradationb. Aerobic degradationc. Oxidationd. None of these2. The major constituent of biogas is ..........a. Ethaneb. Methanec. Propaned. None of these3. Biogas is a mixture of methane, carbon dioxide, hydrogen and oxygen.a. TRUEb. FALSE4. Biogas is a mixture of methane, carbon dioxide, hydrogen sulphide and ...........a. Sulphurb. Oxygenc. Hydrogend. Nitrogen5. ................. bacteria degrades carbon compounds of cow dung and plant wastes to produce biogas.a. Anaerobic bacteriab. Aerobic bacteria