Among the following, which substance turns phenolphthalein to pink?

Options

A. soda water
B. lime water
C. common salt
D. sugar solution

Answer

To determine which substance turns phenolphthalein to pink, we need to understand the behavior of phenolphthalein in different types of solutions. Here’s a step-by-step solution:

### Step 1: Understand Phenolphthalein
Phenolphthalein is a pH indicator that changes color based on the acidity or basicity of a solution. In acidic solutions (pH < 7), phenolphthalein is colorless. In basic solutions (pH > 7), it turns pink.

**Hint:** Remember that phenolphthalein is colorless in acids and pink in bases.

### Step 2: Analyze the Given Options
We have four options to consider:

1. **Soda Water**: Soda water contains carbonic acid (H2CO3), which is an acid. Therefore, it will not turn phenolphthalein pink.

**Hint:** Identify if the substance is acidic or basic.

2. **Lime Water**: Lime water is a solution of calcium hydroxide (Ca(OH)2), which is a base. Since it is basic, it will turn phenolphthalein pink.

**Hint:** Look for hydroxides or substances known to be basic.

3. **Common Salt**: Common salt (NaCl) is neutral. Neutral solutions do not affect the color of phenolphthalein, so it will remain colorless.

**Hint:** Neutral substances do not change the color of phenolphthalein.

4. **Sugar Solution**: A sugar solution is also neutral. Like common salt, it will not affect the color of phenolphthalein, keeping it colorless.

**Hint:** Check if the solution is acidic, basic, or neutral.

### Step 3: Conclusion
Based on the analysis of the options:
- **Option 1 (Soda Water)**: Acidic → Colorless
- **Option 2 (Lime Water)**: Basic → Pink
- **Option 3 (Common Salt)**: Neutral → Colorless
- **Option 4 (Sugar Solution)**: Neutral → Colorless

The only substance that turns phenolphthalein pink is **Lime Water (Option 2)**.

**Final Answer:** Lime Water (Option 2) turns phenolphthalein to pink.