Cobalt chloride method for demonstration of transpiration was first used by

Options

A. Freemenn
B. Stahl
C. Darwin
D. Ganong

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the individual who first used the cobalt chloride method for demonstrating transpiration in plants.

2. **Identifying the Options**: The options provided are Freeman, Stahl, Darwin, and Ganon.

3. **Recalling the Cobalt Chloride Method**: The cobalt chloride method involves using cobalt chloride paper, which is blue in color when dry. When it comes into contact with water, it changes color to pink. This property is crucial for demonstrating transpiration.

4. **Understanding Transpiration**: Transpiration is the process by which water vapor is lost from the aerial parts of plants, primarily through small openings called stomata.

5. **Stahl's Experiment**: Stahl used cobalt chloride paper to demonstrate transpiration by placing the paper at both ends of a leaf. By observing the color change of the paper, he could determine where transpiration was occurring more rapidly.

6. **Conclusion**: Based on the information, the correct answer to the question is Stahl, as he was the one who first used the cobalt chloride method for demonstrating transpiration.

**Final Answer**: The cobalt chloride method for demonstration of transpiration was first used by Stahl.

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