Phenolphthalein is a synthetic indicator and its colours in acidic and basic solutions, respectively are

Options

A. red and blue .
B. blue and red .
C. pink and colourless.
D. colouriess and pink

Answer

To answer the question regarding the colors of phenolphthalein in acidic and basic solutions, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Indicators**:
- Indicators are substances that change color in response to changes in pH. They help us determine whether a solution is acidic or basic.

2. **Identifying Phenolphthalein**:
- Phenolphthalein is a synthetic indicator commonly used in titrations and pH tests.

3. **Color in Acidic Solution**:
- When phenolphthalein is added to an acidic solution (pH < 7), it remains colorless. This indicates that the solution is acidic.

4. **Color in Basic Solution**:
- When phenolphthalein is added to a basic solution (pH > 7), it turns pink. This indicates that the solution is basic.

5. **Final Answer**:
- Therefore, the colors of phenolphthalein in acidic and basic solutions are colorless and pink, respectively.

### Summary:
- In acidic solutions, phenolphthalein is **colorless**.
- In basic solutions, phenolphthalein is **pink**.