Which of the following is the buffer solution ?

Options

A. `CH_(3)COOH+CH_(3)COONa`
B. `CH_(3)COOH + CH_(3)COONH_(4)`
C. `CH_(3)COOH +NH_(4)Cl`
D. `NaOH + NaCl`

Explanation

To determine which of the given options is a buffer solution, we need to understand the criteria for a buffer solution. A buffer solution is typically made up of:

1. A weak acid and its salt with a strong base.
2. A weak base and its salt with a strong acid.

Now, let's analyze the options step by step.

### Step 1: Identify the Components of Each Option
- **Option A**: Contains a weak acid and its salt with a strong base.
- **Option B**: Contains a weak acid and a weak base.
- **Option C**: Contains a weak acid and a salt of a weak base and a strong acid.
- **Option D**: Contains a strong base and a salt.

### Step 2: Analyze Each Option
- **Option A**: If it contains a weak acid (like acetic acid, CH3COOH) and its salt with a strong base (like sodium acetate, CH3COONa), then it qualifies as a buffer solution.
- **Option B**: If it contains a weak acid and a weak base, it does not meet the criteria for a buffer solution.
- **Option C**: If it contains a weak acid and a salt of a weak base with a strong acid, it does not qualify as a buffer solution because the salt must be from a strong base.
- **Option D**: If it contains a strong base and a salt, it does not meet the criteria for a buffer solution.

### Step 3: Conclusion
After analyzing the options, the only option that meets the criteria for a buffer solution is **Option A**.

### Final Answer
**Option A is the buffer solution.**

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