Question

Animal dung is digested to produce biogas (process $A$). The biogas is used in the stove as a fuel (process $B$). Which of the following is correct?

• A. Process $A$ is a chemical change
• B. Process $B$ is a physical change
• C. Both $A$ and $B$ are chemical change
• D. Both $A$ and $B$ are physical change

Answer 1

Answer: (C)

Both $A$ and $B$ are chemical change

The waste materials of plant and animal origin undergo decomposition. On decomposition, a combustible gas chemically known as methane is produced by the action of bacteria. In the process of biogas formation digested slurry is produce that can be used as manure in the field. Thus the process of production of biogas is a chemical process. Biogas undergoes combustion when used as fuel in the stove. Thus the process of using biogas is also a chemical change.

Hence, option C is correct.