Solution P has a pH of 13, solution Q has a pH of 6 and solution R has a pH of 2.
Which solution is a strong acid?

Answer

To determine which solution is a strong acid among the given solutions P, Q, and R based on their pH values, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the pH Values**:
- Solution P: pH = 13
- Solution Q: pH = 6
- Solution R: pH = 2

2. **Understand the pH Scale**:
- The pH scale ranges from 0 to 14.
- A pH of 7 is considered neutral.
- pH values less than 7 indicate acidity, while values greater than 7 indicate basicity.

3. **Categorize the Solutions**:
- Solution P (pH = 13) is basic.
- Solution Q (pH = 6) is acidic.
- Solution R (pH = 2) is acidic.

4. **Determine the Strength of Acids**:
- Strong acids have lower pH values and higher concentrations of hydrogen ions (H⁺).
- The relationship is such that a lower pH indicates a stronger acid.

5. **Compare the Acidic Solutions**:
- Between Solution Q (pH = 6) and Solution R (pH = 2), we see that:
- pH of Solution Q = 6 (weaker acid)
- pH of Solution R = 2 (stronger acid)

6. **Conclusion**:
- Since Solution R has the lowest pH value, it is the strongest acid among the three solutions.

Therefore, **Solution R is the strong acid**.