Which of the following indicator works in the pH range 8 – 9.8 ?

Options

A. Litmus
B. Phenolphthalein
C. Methyl red
D. Methyl orange

Explanation

To determine which indicator works in the pH range of 8 to 9.8, we can analyze the pH ranges of the given indicators.

### Step-by-Step Solution:

1. **Understand the Purpose of an Indicator**:
An indicator is a substance that changes color at a particular pH level. It is used to determine the endpoint of a titration by showing a color change.

2. **Identify the pH Range of Each Indicator**:
- **Litmus**: The pH range for litmus is 4.5 to 8.3. This means it changes color below 8.3, so it does not work in the desired range of 8 to 9.8.
- **Phenolphthalein**: The pH range for phenolphthalein is 8 to 9.8. This means it changes color within the desired range, making it a suitable indicator.
- **Methyl Red**: The pH range for methyl red is 4.2 to 6.2. This is too low for our needs.
- **Methyl Orange**: The pH range for methyl orange is 3.1 to 4.5. This is also too low.

3. **Conclusion**:
Based on the above analysis, the only indicator that works in the pH range of 8 to 9.8 is **Phenolphthalein**.

### Final Answer:
The indicator that works in the pH range 8 to 9.8 is **Phenolphthalein**.

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