`1 M NaCl` and `1 M HCl` are present in an aqueous solution. The solution is

Options

A. Not a buffer solution and with `pH lt 7`
B. Not a buffer solution with `pH gt 7`
C. A buffer solution with `pH lt 7`
D. A buffer solution with `pH gt 7`

Explanation

To determine the nature of the solution containing 1 M NaCl and 1 M HCl, we can follow these steps:

### Step 1: Identify the components of the solution
- The solution contains sodium chloride (NaCl) and hydrochloric acid (HCl).
- NaCl is a neutral salt that does not affect the pH of the solution significantly.
- HCl is a strong acid that completely dissociates in water to produce H⁺ ions and Cl⁻ ions.

### Step 2: Analyze the behavior of HCl in the solution
- Since HCl is a strong acid, it will dissociate completely:
\[ \text{HCl} \rightarrow \text{H}^+ + \text{Cl}^- \]
- The presence of H⁺ ions from HCl means that the solution will be acidic.

### Step 3: Determine if the solution is a buffer
- A buffer solution is one that can resist changes in pH upon the addition of small amounts of acid or base. It typically consists of a weak acid and its conjugate base or a weak base and its conjugate acid.
- In this case, since HCl is a strong acid, it does not have a conjugate base that can accept protons. Therefore, the solution cannot act as a buffer.

### Step 4: Assess the pH of the solution
- Since the solution contains a strong acid (HCl), the pH will be less than 7. The exact pH can be calculated, but we can conclude that it will definitely be acidic due to the high concentration of H⁺ ions.

### Conclusion
- The solution is not a buffer solution, and the pH is less than 7.

### Final Answer
The solution is **not a buffer solution with pH less than 7** (Option A).

---