The `K_(a)` values for `HPO_(4)^(2-)` and `HSO_(3)^(-)` are `4.8xx10^(-13)` and `6.3xx10^(8)` repectively. Therefore, it follows the `HPO_(4)^(2-)` is … acid than `HSO_(3)^(-)` and `PO_(4)^(3-)` is a …… base than `SO_(3)^(2-)`

Options

A. weaker, stronger
B. stronger, weaker
C. weaker, weaker
D. stronger, stronger

Answer

To solve the question, we need to analyze the given \( K_a \) values for the acids \( HPO_4^{2-} \) and \( HSO_3^{-} \) and determine their relative strengths as acids, as well as the strengths of their conjugate bases.

### Step-by-Step Solution:

1. **Identify the Given \( K_a \) Values:**
- For \( HPO_4^{2-} \), \( K_a = 4.8 \times 10^{-13} \)
- For \( HSO_3^{-} \), \( K_a = 6.3 \times 10^{8} \)

2. **Compare the \( K_a \) Values:**
- A higher \( K_a \) value indicates a stronger acid because it means that the acid dissociates more in solution, producing more \( H^+ \) ions.
- Here, \( K_a \) for \( HSO_3^{-} \) is significantly higher than that for \( HPO_4^{2-} \).

3. **Determine the Strength of the Acids:**
- Since \( K_a \) for \( HSO_3^{-} \) (6.3 x 10^8) is greater than \( K_a \) for \( HPO_4^{2-} \) (4.8 x 10^{-13}), we conclude:
- \( HSO_3^{-} \) is a **stronger acid** than \( HPO_4^{2-} \).
- Therefore, \( HPO_4^{2-} \) is a **weaker acid** than \( HSO_3^{-} \).

4. **Identify the Conjugate Bases:**
- The conjugate base of \( HPO_4^{2-} \) is \( PO_4^{3-} \).
- The conjugate base of \( HSO_3^{-} \) is \( SO_3^{2-} \).

5. **Determine the Strength of the Conjugate Bases:**
- The strength of a conjugate base is inversely related to the strength of its corresponding acid. A stronger acid has a weaker conjugate base.
- Since \( HSO_3^{-} \) is a stronger acid than \( HPO_4^{2-} \), it follows that \( SO_3^{2-} \) is a **weaker base** than \( PO_4^{3-} \).
- Conversely, \( HPO_4^{2-} \) being a weaker acid implies that \( PO_4^{3-} \) is a **stronger base** than \( SO_3^{2-} \).

6. **Final Conclusion:**
- Therefore, we can fill in the blanks:
- \( HPO_4^{2-} \) is a **weaker acid** than \( HSO_3^{-} \).
- \( PO_4^{3-} \) is a **stronger base** than \( SO_3^{2-} \).

### Answer:
- \( HPO_4^{2-} \) is a **weaker acid** than \( HSO_3^{-} \).
- \( PO_4^{3-} \) is a **stronger base** than \( SO_3^{2-} \).

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