Which of the following statements is incorrect?

Options

A. Carbon dioxide turns lime water milky.
B. Breaking down of ozone is a chemical change.
C. Production of biogas from animal waste is a physical change.
D. For rusting, the presence of both oxygen and water is essential

Explanation

To determine which of the statements is incorrect, we need to analyze each statement based on the information provided in the video transcript.

1. **Carbon Dioxide and Lime Water**:
- When carbon dioxide is passed through lime water (calcium hydroxide), it forms calcium carbonate, which is a characteristic test for carbon dioxide. This statement is true.

2. **Breaking Down Ozone**:
- The breakdown of ozone (O3) into oxygen (O2) is indeed a chemical change. This statement is also true.

3. **Biogas as a Physical Change**:
- Biogas production involves the decomposition of organic matter, which is a chemical process, not a physical change. Therefore, this statement is incorrect.

4. **Presence of Oxygen and Water**:
- The presence of oxygen and water is typically tested through various methods, and this statement is true.

Based on the analysis above, the incorrect statement is the one regarding biogas being a physical change.

### Step-by-Step Solution:
1. **Identify the statements provided**:
- Analyze each statement regarding carbon dioxide, ozone, biogas, and the presence of oxygen and water.

2. **Evaluate the first statement**:
- Carbon dioxide reacts with lime water to form calcium carbonate. This is a true statement.

3. **Evaluate the second statement**:
- The breakdown of ozone is a chemical change. This is also a true statement.

4. **Evaluate the third statement**:
- Biogas production is a chemical change, not a physical change. This is the incorrect statement.

5. **Evaluate the fourth statement**:
- The presence of oxygen and water can be tested, and this statement is true.

6. **Conclusion**:
- The incorrect statement is about biogas being a physical change.