Which of the following in incorrect about the experiment performed by T.W Engelmann ?

Options

A. Cladophora (a green algae) is used to detect the sites of oxygen evolution.
B. Suspension of aerobic bacteria is used .
C. Bacteria accumulated mainly in the region of orange and green part of the light spectrum.
D. Prism was used to split light into its spectral component.

Answer

To solve the question regarding T.W. Engelmann's experiment, we will analyze each of the statements provided and determine which one is incorrect.

### Step-by-Step Solution:

1. **Understand Engelmann's Experiment**: T.W. Engelmann conducted an experiment to demonstrate the process of photosynthesis using the green alga Cladophora. He aimed to identify the wavelengths of light that are most effective for oxygen production.

2. **Evaluate Statement 1**:
- **Statement**: Cladophora, a green alga, is used to detect the sites of oxygen evolution.
- **Analysis**: This statement is correct because Engelmann used Cladophora to observe where oxygen was being produced during photosynthesis.

3. **Evaluate Statement 2**:
- **Statement**: A suspension of aerobic bacteria is used.
- **Analysis**: This statement is also correct. Engelmann introduced aerobic bacteria into the experiment to detect the presence of oxygen, as these bacteria would accumulate in areas with higher oxygen concentration.

4. **Evaluate Statement 3**:
- **Statement**: Bacteria accumulated mainly in the region of orange and green parts of the light spectrum.
- **Analysis**: This statement is incorrect. Engelmann observed that the bacteria accumulated primarily in the blue and red regions of the light spectrum, where oxygen production was highest.

5. **Evaluate Statement 4**:
- **Statement**: A prism was used to split light into spectral components.
- **Analysis**: This statement is correct. Engelmann used a prism to separate light into its component colors (spectrum) to analyze which wavelengths were most effective for photosynthesis.

6. **Conclusion**: The only incorrect statement is the third one, which claims that bacteria accumulated mainly in the orange and green parts of the light spectrum. Therefore, the answer to the question is that the incorrect statement is option number 3.

### Final Answer:
The incorrect statement about T.W. Engelmann's experiment is: **Bacteria accumulated mainly in the region of orange and green parts of the light spectrum.**

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