Biogas is produced by the breakdown of organic matter like agricultural, waste manure, sewage etc. by anaerobic bacteria (Change X). It is supplied to households where it is burnt as a fuel (Change Y).
Choose the correct statement regarding X and Y.

Options

A. Change X is a chemical change.
B. Change Y is a chemical change.
C. Both changes X and Y are chemical changes.
D. Both changes X and Y are physical changes.

Explanation

To solve the question regarding the changes X and Y in the context of biogas production and its use, we can break down the process step by step.

### Step-by-Step Solution:

1. **Understanding Change X**:
- Change X refers to the breakdown of organic matter (like agricultural waste, manure, sewage) by anaerobic bacteria.
- This process is known as anaerobic digestion, where bacteria decompose organic material in the absence of oxygen.
- During this process, complex organic compounds are broken down into simpler substances, resulting in the production of biogas, primarily composed of methane.

2. **Identifying the Nature of Change X**:
- The breakdown of organic matter is a chemical change because it involves the transformation of substances into new products (biogas).
- Chemical bonds are broken and formed during this process, indicating that a chemical reaction is taking place.

3. **Understanding Change Y**:
- Change Y refers to the burning of biogas as a fuel in households.
- When biogas is burned, it reacts with oxygen to produce carbon dioxide and water, releasing energy in the form of heat.

4. **Identifying the Nature of Change Y**:
- The burning of biogas is also a chemical change because it involves a combustion reaction where new substances (carbon dioxide and water) are formed from the reactants (biogas and oxygen).
- This process also involves the breaking and forming of chemical bonds, indicating a chemical reaction.

5. **Conclusion**:
- Both Change X (the breakdown of organic matter) and Change Y (the burning of biogas) are chemical changes.
- Therefore, the correct statement regarding X and Y is that both changes are chemical changes.

### Final Answer:
Both changes X and Y are chemical changes.