Radioactive isotopes of oxygen `(O""^(18))` was used to know the source of oxygen released through photosynthesis by

Options

A. Hill
B. Van Niel
C. Ruben and Kamen
D. Hatch and Slack

Answer

To answer the question regarding the use of radioactive isotopes of oxygen (O-18) to determine the source of oxygen released during photosynthesis, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Context**:
Photosynthesis is a process where plants convert light energy into chemical energy, producing glucose and releasing oxygen. The question asks about the source of the oxygen released during this process.

2. **Identifying the Isotope**:
The radioactive isotope of oxygen mentioned is O-18. This isotope can be used to trace the source of oxygen in photosynthesis.

3. **Historical Experiments**:
The initial experiment related to the source of oxygen in photosynthesis was conducted by Van Niel. He proposed that the oxygen released during photosynthesis comes from water, not from carbon dioxide.

4. **Further Validation**:
Rubin and Kamen conducted experiments using O-18 to validate Van Niel's hypothesis. They used radioactive water (H2O with O-18) and carbon dioxide (CO2 with O-18) to trace the origin of the oxygen released.

5. **Experimental Procedure**:
- In the first part of their experiment, they supplied plants with radioactive water. They observed that the oxygen released during photosynthesis contained the radioactive isotope, indicating that the oxygen came from water.
- In the second part, they used radioactive carbon dioxide and found that the oxygen released did not contain the radioactive isotope, indicating that the oxygen released during photosynthesis actually comes from water, not carbon dioxide.

6. **Conclusion**:
The results of Rubin and Kamen's experiments confirmed that the oxygen released during photosynthesis originates from water (H2O) and not from carbon dioxide (CO2). Therefore, the correct answer to the question is that the experiments were conducted by Rubin and Kamen.

### Final Answer:
The radioactive isotopes of oxygen (O-18) were used to determine the source of oxygen released through photosynthesis by Rubin and Kamen.

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