Which solution is not a buffer solution ?

Options

A. `NaCN ` ( 2 mole) `+ HCl` ( 1 mole ) in `5L`
B. `NaCN ` (1 mole ) `+ HCl` (1 molde ) in `5L`
C. `NH_(3) `(2 mole ) `+ HCl ` ( 1 mole) in `5L`
D. `CH_(3)COOH` ( 2 mole) `+ KOH` (1 mole ) in `5L`

Explanation

To determine which solution is not a buffer solution, we need to first understand what a buffer solution is.

### Step-by-Step Solution:

1. **Definition of Buffer Solution**: A buffer solution is a solution that resists changes in pH when small amounts of an acid or base are added. It is typically composed of:
- A weak acid and its salt (e.g., acetic acid and sodium acetate).
- A weak base and its salt (e.g., ammonia and ammonium chloride).

2. **Characteristics of Buffer Solutions**:
- They maintain a relatively stable pH.
- They can neutralize small amounts of added acids or bases.

3. **Analyzing Given Solutions**:
- We need to evaluate the options provided (though not listed in the question) to identify which solution does not meet the criteria of a buffer solution.

4. **Example Analysis**:
- If we consider a solution made from one mole of sodium cyanide (NaCN) and hydrochloric acid (HCl):
- NaCN is the salt of a weak acid (HCN) and can act as a base.
- HCl is a strong acid.
- Mixing NaCN with HCl does not create a buffer because HCl will completely dissociate and react with NaCN, leading to a significant change in pH.

5. **Conclusion**: Based on the analysis, the combination of NaCN and HCl does not form a buffer solution. Therefore, this is the solution that is not a buffer.

### Final Answer:
The solution that is not a buffer solution is the one formed by combining sodium cyanide (NaCN) and hydrochloric acid (HCl).

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