In half-leaf experiment, a compound is used to absorb `CO_(2)`. This compound is

Options

A. NaOH
B. KOH
C. NaCl
D. HCl

Answer

### Step-by-Step Solution:

1. **Understanding the Experiment**: The half-leaf experiment, also known as the moles experiment, is designed to study the process of photosynthesis in plants. It specifically examines the role of carbon dioxide (CO2) in the photosynthesis process.

2. **Setup of the Experiment**: In this experiment, a plant leaf is divided into two halves. One half of the leaf is submerged in a solution, while the other half remains exposed to the air.

3. **Use of KOH Solution**: The solution used in the experiment is potassium hydroxide (KOH). This compound is known for its ability to absorb carbon dioxide from the environment.

4. **Absorption of CO2**: The half of the leaf that is dipped in the KOH solution will absorb CO2 from the air. As a result, this half of the leaf will not have access to CO2, which is essential for photosynthesis.

5. **Observation of Starch Production**: After exposing the plant to sunlight for a certain period, the leaf is tested for the presence of starch. The half of the leaf that was not dipped in KOH will show the presence of starch, indicating that photosynthesis occurred there due to the availability of CO2. Conversely, the half of the leaf that was in the KOH solution will show no starch, as CO2 was not available for photosynthesis.

6. **Conclusion**: The experiment demonstrates that CO2 is essential for photosynthesis, and the compound used to absorb CO2 in this experiment is potassium hydroxide (KOH).

### Final Answer:
The compound used to absorb CO2 in the half-leaf experiment is **potassium hydroxide (KOH)**.