In the Fountain experiment with ammonia, the colour of the fountain is 

Options

A. Red
B. Blue
C. Pink
D. Dark green

Answer

### Step-by-Step Solution:

1. **Understanding the Fountain Experiment**:
- The fountain experiment involves a setup with two round-bottom flasks connected by a tube. One flask is filled with water and phenolphthalein, while the other flask contains ammonia gas.

2. **Setup Description**:
- The flask containing water and phenolphthalein is positioned below the flask containing ammonia gas. A clamp is used to control the flow of water.

3. **Opening the Clamp**:
- When the clamp is opened, water is drawn up from the lower flask into the upper flask. This movement is due to the pressure difference created by the ammonia gas.

4. **Role of Phenolphthalein**:
- Phenolphthalein is a pH indicator that changes color in response to the acidity or basicity of a solution. In a basic environment, it turns pink.

5. **Effect of Ammonia**:
- Ammonia (NH3) is a basic gas. When it comes into contact with the phenolphthalein in the water, it raises the pH of the solution, making it basic.

6. **Observation of Color Change**:
- As the water containing phenolphthalein rises and mixes with ammonia, the solution turns pink due to the basic nature of ammonia.

7. **Conclusion**:
- Therefore, in the fountain experiment with ammonia, the color of the fountain is pink.

### Final Answer:
The color of the fountain in the experiment with ammonia is **pink**.

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