Conjugate base the Bronsted acids ` H_2O ` and HF are :

Options

A. ` OH^(-) and F^(-) , ` respectively
B. `H_3O^(+) and H_2F^(+) ` ,respectively
C. `OH^(-) and H_2F^(+) ` , respectively
D. ` H_3O^(+) and F^(-) ` , respectively

Answer

To find the conjugate bases of the Bronsted acids \( H_2O \) (water) and \( HF \) (hydrofluoric acid), we need to understand the concept of Bronsted acids and bases.

### Step-by-Step Solution:

1. **Identify the Bronsted Acids**:
- We have two acids: \( H_2O \) and \( HF \).

2. **Define Bronsted Acid**:
- A Bronsted acid is a substance that donates a proton (\( H^+ \)) to another substance.

3. **Determine the Conjugate Base of \( H_2O \)**:
- When \( H_2O \) acts as an acid, it donates a proton (\( H^+ \)).
- The reaction can be represented as:
\[ H_2O \rightarrow H^+ + OH^- \]
- After donating a proton, the remaining species is \( OH^- \) (hydroxide ion), which is the conjugate base of water.

4. **Determine the Conjugate Base of \( HF \)**:
- When \( HF \) acts as an acid, it also donates a proton (\( H^+ \)).
- The reaction can be represented as:
\[ HF \rightarrow H^+ + F^- \]
- After donating a proton, the remaining species is \( F^- \) (fluoride ion), which is the conjugate base of hydrofluoric acid.

5. **Summarize the Conjugate Bases**:
- The conjugate base of \( H_2O \) is \( OH^- \).
- The conjugate base of \( HF \) is \( F^- \).

6. **Final Answer**:
- Therefore, the conjugate bases of the Bronsted acids \( H_2O \) and \( HF \) are \( OH^- \) and \( F^- \) respectively.

### Conclusion:
The correct option is the first one: \( OH^- \) and \( F^- \) respectively.