Let's classify each substance based on its pH value:
1. Pure water (pH = 7.0):
- The pH scale ranges from 0 to 14, where a pH of 7 is considered neutral.
- Since the pH of pure water is exactly 7.0, it is neutral.
Therefore, pure water is neutral.
2. Lake water (pH = 6.5):
- A pH value less than 7 indicates an acidic substance.
- Since the pH of lake water is 6.5, which is less than 7, it is acidic.
Therefore, lake water is acidic.
3. Baking soda solution (pH = 9):
- A pH value greater than 7 indicates a basic (or alkaline) substance.
- Since the pH of the baking soda solution is 9, which is greater than 7, it is basic.
Therefore, the baking soda solution is basic.
4. Soapy water (pH = 12):
- A pH value greater than 7 indicates a basic substance.
- Since the pH of soapy water is 12, which is significantly greater than 7, it is basic.
Therefore, soapy water is basic.
In conclusion:
- Pure water is neutral.
- Lake water is acidic.
- Baking soda solution is basic.
- Soapy water is basic.
