IV: Select the correct answer from the given choices Which one of the following is a diprotic acid? \( \begin{array}{ll}\text { a. Hydrochloric acid } & \text { c. Sulfuric acid } \\ \text { b. Phosphoric acid } & \text { d. Acetic acid } \\ \text { Which of the following is not the characteristic of an acid: } \\ \begin{array}{ll}\text { a. An acid changes the color of an indicator }\end{array}\end{array} \$ \)

To determine which of the given acids is a diprotic acid, we need to understand what a diprotic acid is. A diprotic acid is an acid that can donate two protons (H⁺ ions) per molecule in an aqueous solution. Let's analyze the options: 1. **Hydrochloric acid (HCl)**: This is a monoprotic acid because it can donate only one proton. 2. **Sulfuric acid (H₂SO₄)**: This is a diprotic acid because it can donate two protons. 3. **Phosphoric acid (H₃PO₄)**: This is a triprotic acid because it can donate three protons. 4. **Acetic acid (CH₃COOH)**: This is a monoprotic acid because it can donate only one proton. From this analysis, the correct answer for the diprotic acid is: **c. Sulfuric acid** Now, regarding the second part of the question about the characteristic of an acid, the statement provided is: - **a. An acid changes the color of an indicator**: This is indeed a characteristic of acids, as they can change the color of pH indicators. Since the question asks for which of the following is not a characteristic of an acid, we would need more options to determine if there is a statement that does not describe an acid. However, based on the provided statement, it is a characteristic of acids. In summary: - The diprotic acid is **c. Sulfuric acid**. - The statement about changing the color of an indicator is a characteristic of acids.