The main constituent of biogas (gobar gas) is: MCQ with Answer and Explanation

Explanation:
Graphite, an allotrope of carbon, is a good conductor of electricity. This is because each carbon atom is bonded to three others, leaving one free valence electron per atom that is delocalized and can move freely between the layers to conduct electricity, unlike diamond which is an insulator.

Explanation:
Combustion of methane (CH₄ + 2O₂ → CO₂ + 2H₂O + heat) is an exothermic reaction, releasing heat to surroundings. Melting, evaporation, and sublimation are endothermic phase changes requiring heat absorption to overcome intermolecular forces. Exothermic reactions: burning, respiration, neutralization (usually), condensation, freezing. Endothermic: photosynthesis, cooking, melting, boiling.

Explanation:
Catalase is an enzyme found in nearly all living organisms, particularly high in liver and red blood cells. It catalyzes the decomposition of toxic hydrogen peroxide to water and oxygen: 2H₂O₂ → 2H₂O + O₂. This protects cells from oxidative damage. It has one of the highest turnover numbers. Stomach has pepsin.