The correct option is **B. Acids donate protons (H⁺) while bases accept protons (H⁺).** ### Detailed Explanation: 1. **Understanding Acids and Bases:** - The behavior of acids and bases in aqueous solutions is primarily described by the Brønsted-Lowry theory. According to this theory: - **Acids** are substances that can donate protons (H⁺ ions). - **Bases** are substances that can accept protons (H⁺ ions). 2. **Why Option B is Correct:** - When an acid dissolves in water, it releases H⁺ ions into the solution. For example, hydrochloric acid (HCl) dissociates in water as follows: \[ \text{HCl} \rightarrow \text{H}^+ + \text{Cl}^- \] - In this reaction, HCl donates a proton (H⁺), which is characteristic of acids. - Conversely, when a base is present in the solution, it can accept these protons. For instance, ammonia (NH₃) can accept a proton to form ammonium (NH₄⁺): \[ \text{NH}_3 + \text{H}^+ \rightarrow \text{NH}_4^+ \] - This demonstrates that bases accept protons, aligning perfectly with the definition provided in option B. 3. **Why the Other Options are Incorrect:** - **Option A: Acids donate hydroxide ions (OH⁻) while bases donate protons (H⁺).** - This statement is incorrect because acids do not donate hydroxide ions; they donate protons (H⁺). Hydroxide ions (OH⁻) are typically associated with bases, not acids. - **Option C: Acids and bases both donate hydroxide ions (OH⁻).** - This is incorrect because acids do not donate hydroxide ions. Instead, they release protons (H⁺). Bases, on the other hand, can produce hydroxide ions in solution (e.g., NaOH dissociates to give Na⁺ and OH⁻). - **Option D: Acids accept protons (H⁺) while bases donate hydroxide ions (OH⁻).** - This statement is also incorrect. Acids do not accept protons; they donate them. While bases can produce hydroxide ions, they are defined as proton acceptors, not as donors of hydroxide ions. ### Summary of Key Concepts: - **Acids**: Substances that donate protons (H⁺) in aqueous solutions. - **Bases**: Substances that accept protons (H⁺) in aqueous solutions. - The Brønsted-Lowry theory is fundamental in understanding acid-base behavior. - Misunderstanding the definitions can lead to confusion about the nature of acids and bases. ### Revision Summary: - Acids donate protons (H⁺), while bases accept protons (H⁺). - Hydroxide ions (OH⁻) are associated with bases, not acids. - The Brønsted-Lowry theory is key to understanding acid-base reactions. - Always remember the definitions to avoid confusion in exam scenarios.