Which of the following is a conjugated acid - base pair?

Options

A. CHl,NaOH
B. `NH_4Cl,NH_4Br`
C. `H_2SO_4,HSO_4^(-)`
D. KCN , KON

Answer

To determine which of the following is a conjugate acid-base pair, we need to understand the concept of conjugate acids and bases. A conjugate acid-base pair consists of two species that differ by the presence or absence of a proton (H⁺ ion).

### Step-by-Step Solution:

1. **Identify the Definitions**:
- A **conjugate acid** is formed when a base gains a proton (H⁺).
- A **conjugate base** is formed when an acid loses a proton (H⁺).

2. **Select a Reaction**:
- Consider a common acid-base reaction, such as the reaction of sulfuric acid (H₂SO₄) with water (H₂O).

3. **Write the Reaction**:
- When H₂SO₄ donates a proton to water, the reaction can be written as:
\[ \text{H₂SO₄} + \text{H₂O} \rightarrow \text{H₃O}^+ + \text{HSO₄}^- \]

4. **Identify the Conjugate Acid and Base**:
- In this reaction:
- H₂SO₄ acts as an acid because it donates a proton (H⁺) to water.
- HSO₄⁻ is the conjugate base of H₂SO₄ because it is what remains after H₂SO₄ loses a proton.
- H₃O⁺ is the conjugate acid formed when water gains a proton.

5. **Conclude the Pair**:
- Therefore, the conjugate acid-base pair in this reaction is H₂SO₄ (acid) and HSO₄⁻ (base).

### Final Answer:
The conjugate acid-base pair is **H₂SO₄ and HSO₄⁻**.

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