When phenolphthalein is added to an aqueous solution containing one of the following solutes the solution turns pink. When solute is present?

Options

A. `NaCI`
B. `KC_(2)H_(3)O_(2)`
C. `LiBr`
D. `NH_(4)NO_(3)`

Explanation

To determine which solute causes the solution to turn pink when phenolphthalein is added, we need to analyze the nature of each solute and its effect on the pH of the solution. Phenolphthalein is an acid-base indicator that turns pink in basic solutions (pH > 8.2) and remains colorless in acidic solutions (pH < 8.2).

### Step-by-Step Solution:

1. **Understanding Phenolphthalein**:
- Phenolphthalein is an acid-base indicator that turns pink in basic solutions and colorless in acidic solutions.

**Hint**: Remember that the color change of phenolphthalein indicates the pH of the solution.

2. **Analyzing the Solutes**:
- **Option A: NaCl**
- Sodium chloride (NaCl) is a neutral salt formed from a strong acid (HCl) and a strong base (NaOH). Its solution has a pH of around 7, which is neutral.
- **Conclusion**: This will not turn pink.

**Hint**: Neutral solutions do not affect the color of phenolphthalein.

- **Option B: Potassium Acetate (CH3COOK)**
- Potassium acetate dissociates in water to form potassium ions (K⁺) and acetate ions (CH3COO⁻). The acetate ion can react with water to produce hydroxide ions (OH⁻), making the solution basic.
- **Conclusion**: This will turn pink due to the basic nature of the solution.

**Hint**: Look for solutes that produce hydroxide ions in solution.

- **Option C: LiBr**
- Lithium bromide (LiBr) dissociates into lithium ions (Li⁺) and bromide ions (Br⁻). The solution is slightly basic due to the presence of LiOH, but it is close to neutral.
- **Conclusion**: This will not turn pink.

**Hint**: Slightly basic solutions may not be sufficient to turn phenolphthalein pink.

- **Option D: Ammonium Nitrate (NH4NO3)**
- Ammonium nitrate dissociates into ammonium ions (NH4⁺) and nitrate ions (NO3⁻). The ammonium ion can react with water to produce hydronium ions (H3O⁺), making the solution acidic.
- **Conclusion**: This will not turn pink.

**Hint**: Acidic solutions will keep phenolphthalein colorless.

3. **Final Conclusion**:
- The only solute that causes the solution to turn pink when phenolphthalein is added is **Potassium Acetate (Option B)**.

### Answer:
**The solution turns pink when Potassium Acetate (CH3COOK) is present.**