In the following `[Alunderset((p))((H_2O)_6)]^(3+)+underset((q))(HCO_3^(-))hArr[Alunderset(" "(r))((H_2O)_5)OH]^(2+)+H_2underset((s))(CO_3)` species behaving as Brosnted - Lowry acids are

Options

A. (p),(s)
B. (q),(r)
C. (q),(s)
D. (p),(r)

Answer

To solve the question, we need to identify the species that behave as Brønsted-Lowry acids in the given reaction. A Brønsted-Lowry acid is defined as a species that donates a proton (H⁺) to another species.

### Step-by-Step Solution:

1. **Identify the Species in the Reaction:**
The reaction given is:
\[ [Al(H_2O)_6]^{3+} + HCO_3^{-} \rightleftharpoons [Al(H_2O)_5OH]^{2+} + H_2CO_3 \]
Here, we have:
- \( [Al(H_2O)_6]^{3+} \)
- \( HCO_3^{-} \)
- \( [Al(H_2O)_5OH]^{2+} \)
- \( H_2CO_3 \)

2. **Analyze Each Species:**
- **\( [Al(H_2O)_6]^{3+} \)**: This complex has 6 water molecules coordinated to aluminum. When it donates a proton, it forms \( [Al(H_2O)_5OH]^{2+} \). Therefore, it acts as a Brønsted-Lowry acid.
- **\( HCO_3^{-} \)**: This species can accept a proton to form \( H_2CO_3 \). It does not donate a proton, so it does not act as a Brønsted-Lowry acid in this reaction.
- **\( [Al(H_2O)_5OH]^{2+} \)**: This is the conjugate base formed from \( [Al(H_2O)_6]^{3+} \) after it donates a proton. It does not act as an acid.
- **\( H_2CO_3 \)**: This species is formed when \( HCO_3^{-} \) accepts a proton. It acts as a Brønsted-Lowry acid.

3. **Conclusion:**
The species that behave as Brønsted-Lowry acids in this reaction are:
- \( [Al(H_2O)_6]^{3+} \) (denoted as \( P \))
- \( H_2CO_3 \) (denoted as \( S \))

Thus, the answer is \( P \) and \( S \).