Which of the following is not the characteristic of an acid. a. An acid changes the color of an indicator b. An acid has a bitter taste c. An acid ionizes in water d. An acid produces hydronium ions in water

The correct answer is: **b. An acid has a bitter taste** ### Explanation: **Characteristics of Acids:** 1. **Change the Color of an Indicator (a):** Acids can change the color of pH indicators. For example, they turn blue litmus paper red. 2. **Ionize in Water (c):** Acids ionize in water to release hydrogen ions (H⁺). 3. **Produce Hydronium Ions in Water (d):** When an acid dissolves in water, it forms hydronium ions (H₃O⁺), which are responsible for the acidic properties. **Incorrect Characteristic:** - **Bitter Taste (b):** Acids typically have a **sour** taste, not bitter. A bitter taste is more characteristic of **bases** (alkaline substances). Thus, **option b** is **not** a characteristic of acids.