To determine which substance is closest to being neutral on the pH scale, we need to look at the absolute difference between the pH value of each substance and the neutral pH value of 7.
Here's how we can do that step by step:
1. Identify the pH of each substance:
- Shampoo: pH 6
- Lemon juice: pH 2
- Tomato juice: pH 4
- Liquid drain cleaner: pH 14
2. Determine the neutral pH value:
- The neutral pH value is 7.
3. Calculate the absolute difference between the pH of each substance and the neutral pH:
- For Shampoo: \( |6 - 7| = 1 \)
- For Lemon juice: \( |2 - 7| = 5 \)
- For Tomato juice: \( |4 - 7| = 3 \)
- For Liquid drain cleaner: \( |14 - 7| = 7 \)
4. Compare the absolute differences to find the smallest one:
- Shampoo: 1
- Lemon juice: 5
- Tomato juice: 3
- Liquid drain cleaner: 7
5. Identify the substance with the smallest absolute difference to the neutral pH:
- The smallest absolute difference is 1, which corresponds to Shampoo.
Therefore, Shampoo is the substance that is closest to being neutral on the pH scale.
