Which one of the following in not a Bronsted-Lowery acid ?

Options

A. HCl
B. `HNO_3`
C. `CH_3COOH`
D. `BF_3`

Explanation

To determine which of the following compounds is not a Bronsted-Lowry acid, we need to understand the definition of a Bronsted-Lowry acid. A Bronsted-Lowry acid is defined as a substance that can donate a proton (H⁺ ion) to another substance.

Let's analyze the given options:

1. **HCl (Hydrochloric acid)**:
- HCl is a strong acid that dissociates in water to produce H⁺ ions.
- Therefore, HCl can donate a proton and is a Bronsted-Lowry acid.

2. **HNO3 (Nitric acid)**:
- HNO3 is also a strong acid and dissociates in water to release H⁺ ions.
- Thus, HNO3 can donate a proton and is a Bronsted-Lowry acid.

3. **CH3COOH (Acetic acid)**:
- Acetic acid contains hydrogen that can be donated as H⁺ when it dissociates in solution.
- Therefore, CH3COOH can also donate a proton and is a Bronsted-Lowry acid.

4. **BF3 (Boron trifluoride)**:
- BF3 does not contain any hydrogen atoms.
- Since it cannot donate a proton (H⁺), it does not qualify as a Bronsted-Lowry acid.

Based on this analysis, the compound that is not a Bronsted-Lowry acid is **BF3**.

### Final Answer:
**BF3** is not a Bronsted-Lowry acid.