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 need to analyze the pH ranges of the given indicators: litmus, phenolphthalein, methyl red, and methyl orange.

### Step-by-Step Solution:

1. **Identify the pH ranges of the indicators:**
- **Litmus**: Changes color around pH 5 to 8 (red in acidic, blue in basic).
- **Phenolphthalein**: Changes color in the pH range of approximately 8 to 10 (colorless in acidic, pink in basic).
- **Methyl Red**: Changes color in the pH range of 4.8 to 6.0 (red in acidic, yellow in neutral to basic).
- **Methyl Orange**: Changes color in the pH range of 3.1 to 4.4 (red in acidic, yellow in neutral).

2. **Determine which indicator fits the specified pH range (8 to 9.8):**
- **Litmus**: Does not fit, as it changes color below pH 8.
- **Phenolphthalein**: Fits perfectly, as it changes color from colorless to pink between pH 8 and 10.
- **Methyl Red**: Does not fit, as it changes color below pH 6.
- **Methyl Orange**: Does not fit, as it changes color below pH 4.4.

3. **Conclusion:**
- The only indicator that works in the pH range of 8 to 9.8 is **Phenolphthalein**.

### Final Answer:
The correct option is **Phenolphthalein**.

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