The no. of conjugate acid-base pairs present in the aqueous solution of `H_(3)PO_(3)` is

Options

A. `2`
B. `3`
C. `4`
D. `5`

Explanation

To determine the number of conjugate acid-base pairs present in the aqueous solution of \( H_3PO_3 \), we can follow these steps:

### Step 1: Understand the concept of conjugate acid-base pairs
Conjugate acid-base pairs are pairs of compounds that differ by one proton (H⁺). When an acid donates a proton, it becomes its conjugate base, and when a base accepts a proton, it becomes its conjugate acid.

### Step 2: Identify the dissociation of \( H_3PO_3 \)
The dissociation of \( H_3PO_3 \) (phosphorous acid) in water can be represented as follows:
1. \( H_3PO_3 \) dissociates to form \( H_2PO_3^- \) and \( H^+ \):
\[ H_3PO_3 \rightleftharpoons H_2PO_3^- + H^+ \]

### Step 3: Further dissociation of the products
The product \( H_2PO_3^- \) can further dissociate:
2. \( H_2PO_3^- \) dissociates to form \( HPO_3^{2-} \) and \( H^+ \):
\[ H_2PO_3^- \rightleftharpoons HPO_3^{2-} + H^+ \]

3. Finally, \( HPO_3^{2-} \) can dissociate:
\[ HPO_3^{2-} \rightleftharpoons PO_3^{3-} + H^+ \]

### Step 4: Identify the conjugate acid-base pairs
From the dissociation reactions, we can identify the following conjugate acid-base pairs:
1. \( H_3PO_3 \) and \( H_2PO_3^- \)
2. \( H_2PO_3^- \) and \( HPO_3^{2-} \)
3. \( HPO_3^{2-} \) and \( PO_3^{3-} \)

### Step 5: Count the conjugate acid-base pairs
We have identified three conjugate acid-base pairs:
1. \( H_3PO_3 / H_2PO_3^- \)
2. \( H_2PO_3^- / HPO_3^{2-} \)
3. \( HPO_3^{2-} / PO_3^{3-} \)

Thus, the total number of conjugate acid-base pairs in the aqueous solution of \( H_3PO_3 \) is **3**.

### Final Answer
The number of conjugate acid-base pairs present in the aqueous solution of \( H_3PO_3 \) is **3**.

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