The following equilibrium is established when hydrogen chloride is dissolved in acetic acid `HCl(aq)+CH_3COOH(aq)hArrCl^(-)(aq)+CH_3COOH_2^(+)(aq)`
The set that characterises the conjugate acid-base pairs is :

Options

A. `(HCl, CH_(3)COOH)` and `(CH_(3)COOH_(2)^(+), Cl^(-))`
B. `(HCl, CH_(3)COOH_(2)^(+))` and `(CH_(3)COOH, Cl^(-))`
C. `( CH_(3)COOH_(2)^(+), HCl)` and `( Cl^(-), CH_(3)COOH)`
D. `(HCl, Cl^(-))` and `(CH_(3)COOH_(2)^(+), CH_(3)COOH)`

Explanation

To determine the conjugate acid-base pairs from the given equilibrium reaction:

**Equilibrium Reaction:**
\[ \text{HCl(aq)} + \text{CH}_3\text{COOH(aq)} \rightleftharpoons \text{Cl}^-(aq) + \text{CH}_3\text{COOH}_2^+(aq) \]

### Step-by-Step Solution:

1. **Identify the Acid and Base:**
- In the reaction, HCl acts as a strong acid that donates a proton (H⁺) to the acetic acid (CH₃COOH).
- CH₃COOH is a weak acid that can also accept a proton, thus acting as a base in this context.

2. **Determine the Conjugate Base:**
- When HCl donates a proton (H⁺), it transforms into its conjugate base, which is Cl⁻.
- Therefore, the conjugate base of HCl is Cl⁻.

3. **Determine the Conjugate Acid:**
- When CH₃COOH accepts a proton (H⁺) from HCl, it becomes CH₃COOH₂⁺.
- Thus, the conjugate acid of CH₃COOH is CH₃COOH₂⁺.

4. **Identify the Conjugate Acid-Base Pairs:**
- The pairs identified from the reaction are:
- HCl (acid) and Cl⁻ (conjugate base)
- CH₃COOH (base) and CH₃COOH₂⁺ (conjugate acid)

5. **Conclusion:**
- The correct set that characterizes the conjugate acid-base pairs from the reaction is:
- HCl and Cl⁻ (acid and conjugate base)
- CH₃COOH and CH₃COOH₂⁺ (base and conjugate acid)

### Final Answer:
The set that characterizes the conjugate acid-base pairs is:
- HCl and Cl⁻
- CH₃COOH and CH₃COOH₂⁺

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