**Correct Option: D. W is the most acidic solution** ### Explanation of the Correct Answer To determine which solution is the most acidic, we need to understand what pH represents. The pH scale ranges from 0 to 14, where: - A pH less than 7 indicates an acidic solution. - A pH of 7 is neutral (pure water). - A pH greater than 7 indicates a basic (alkaline) solution. Given the pH values of the solutions: - W: pH 4 - X: pH 6 - Y: pH 8 - Z: pH 10 **Step 1: Identify the acidity of each solution.** - **Solution W (pH 4)**: This is acidic because it is less than 7. - **Solution X (pH 6)**: This is also acidic, but less so than W. - **Solution Y (pH 8)**: This is basic, as it is greater than 7. - **Solution Z (pH 10)**: This is also basic. **Step 2: Compare the acidic solutions.** Among the solutions W and X, W has a lower pH (4) compared to X (6). The lower the pH, the higher the concentration of hydrogen ions (H⁺), which means W is more acidic than X. **Conclusion**: Since W is the only solution with a pH below 7, it is indeed the most acidic solution. ### Explanation of Why Other Options Are Incorrect **Option A: None of these solutions is acidic.** - This option is incorrect because both W (pH 4) and X (pH 6) are acidic solutions. Therefore, it is false to say that none of the solutions is acidic. **Option B: The pH of Y is made more acidic by the addition of distilled water.** - This option is misleading. Adding distilled water (which has a neutral pH of 7) to solution Y (pH 8) would dilute the solution, potentially lowering the concentration of hydroxide ions (OH⁻) but not making it acidic. Instead, it would move the pH closer to neutral (7), not more acidic. Thus, this statement is incorrect. **Option C: Z is the most acidic solution.** - This option is incorrect because Z has a pH of 10, which is basic. The most acidic solution is W with a pH of 4. Therefore, Z cannot be the most acidic solution. ### Summary of Key Points - The pH scale indicates acidity (pH < 7) and basicity (pH > 7). - Solution W (pH 4) is the most acidic among the given solutions. - Solutions X (pH 6) is also acidic but less so than W. - Solutions Y (pH 8) and Z (pH 10) are basic and not acidic. ### Revision Summary - pH < 7 indicates acidity; pH = 7 is neutral; pH > 7 indicates basicity. - W (pH 4) is the most acidic solution. - Adding distilled water to a solution does not make it more acidic; it dilutes the solution. - Always compare pH values directly to determine acidity.