To determine which substance is closest to being neutral on the pH scale, we need to compare their pH values to the neutral pH value, which is \(7\). The closer a substance's pH value is to \(7\), the closer it is to being neutral.
Here's the step-by-step process to find the closest substance:
1. Identify the pH values of the substances:
- Shampoo: \(6\)
- Lemon juice: \(2\)
- Tomato juice: \(4\)
- Liquid drain cleaner: \(14\)
2. Calculate the absolute difference between the pH value of each substance and the neutral pH value of \(7\):
- For Shampoo: The difference is \(|6 - 7| = 1\).
- For Lemon juice: The difference is \(|2 - 7| = 5\).
- For Tomato juice: The difference is \(|4 - 7| = 3\).
- For Liquid drain cleaner: The difference is \(|14 - 7| = 7\).
3. Compare these differences to find the smallest one, since the smallest difference will indicate the substance closest to neutral:
- Shampoo: \(1\)
- Lemon juice: \(5\)
- Tomato juice: \(3\)
- Liquid drain cleaner: \(7\)
4. Determine the smallest absolute difference:
- The smallest difference is \(1\), which corresponds to Shampoo.
Therefore, the substance closest to being neutral on the pH scale is Shampoo.
Answer: Shampoo
