`PCl_(3) + H_(2)O to B + HCl` where B is product of complete hydrolysis.
The basicity of compound B will be :

Options

A. 1
B. 3
C. 2
D. None of these.

Explanation

To solve the question regarding the basicity of compound B formed from the reaction of PCl₃ with H₂O, we will follow these steps:

### Step 1: Identify the Reaction
The reaction of phosphorus trichloride (PCl₃) with water (H₂O) can be represented as:
\[ \text{PCl}_3 + \text{H}_2\text{O} \rightarrow \text{B} + \text{HCl} \]

### Step 2: Determine the Product B
When PCl₃ reacts with water, it undergoes hydrolysis to form phosphorous acid (H₃PO₃) and hydrochloric acid (HCl). The balanced equation for the reaction is:
\[ \text{PCl}_3 + 3\text{H}_2\text{O} \rightarrow \text{H}_3\text{PO}_3 + 3\text{HCl} \]
Thus, the product B is H₃PO₃ (orthophosphorous acid).

### Step 3: Understand Basicity
Basicity refers to the ability of a compound to accept protons (H⁺ ions). The basicity of an acid is determined by the number of ionizable hydrogen atoms it has.

### Step 4: Analyze the Structure of B (H₃PO₃)
The structure of orthophosphorous acid (H₃PO₃) can be represented as:
- It has one phosphorus atom (P) double bonded to one oxygen atom (O) and single bonded to two hydroxyl groups (OH) and one hydrogen atom (H).
- The structure can be depicted as:
\[ \text{P} = \text{O} \]
\[ \text{OH} \]
\[ \text{OH} \]
\[ \text{H} \]

### Step 5: Count Ionizable Hydrogens
In H₃PO₃, there are two hydroxyl (OH) groups that can release protons, and one hydrogen atom that is not part of a hydroxyl group. Therefore, the ionizable hydrogens are from the two OH groups.

### Step 6: Determine the Basicity
Since there are two ionizable hydrogen atoms in H₃PO₃, it behaves as a dibasic acid. Thus, the basicity of compound B (H₃PO₃) is 2.

### Conclusion
The basicity of compound B (H₃PO₃) is 2.