Which chemical is used to detect transpiration comparatively?

Options

A. Calcium carbonate
B. Cobalt carbonate
C. Cobalt chloride
D. Mercuric acetate

Answer

To determine which chemical is used to detect transpiration comparatively, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Transpiration**: Transpiration is the process by which plants lose water vapor through small openings called stomata. It is essential for nutrient transport and temperature regulation in plants.

2. **Evaluate the Options**: The question provides several chemical options. We need to analyze each one to see if it is related to detecting transpiration.

3. **Option 1 - Calcium Carbonate**: This chemical is primarily used to supply calcium to plants and does not have a role in detecting transpiration. Therefore, this option is incorrect.

4. **Option 2 - Cobalt Carbonate**: Similar to calcium carbonate, cobalt carbonate is not used for detecting transpiration. It is more related to providing cobalt for plant nutrition. Hence, this option is also incorrect.

5. **Option 3 - Cobalt Chloride**: This chemical is known to change color in the presence of moisture. When cobalt chloride is dry, it is blue, and when it absorbs water, it turns pink. This property makes cobalt chloride a suitable indicator for detecting transpiration. Thus, this option is correct.

6. **Option 4 - Murmuric Acetate**: This chemical acts as an anti-transpirant, meaning it prevents transpiration rather than detecting it. Therefore, this option is incorrect.

7. **Conclusion**: Based on the analysis, the correct answer is **Cobalt Chloride**, as it is the chemical used to detect transpiration comparatively.

### Final Answer:
The chemical used to detect transpiration comparatively is **Cobalt Chloride**.