`PCl_(5)+H_(2)Oto B+HCI`
`B+H_(2)O to C+HCI`
The basicity of compound C will be:

Options

A. 1
B. 3
C. 2
D. none of the above

Explanation

To solve the problem, we need to analyze the given reactions step by step and determine the basicity of compound C.

### Step 1: Identify the first reaction
The first reaction is:
\[ \text{PCl}_5 + \text{H}_2\text{O} \rightarrow B + \text{HCl} \]

In this reaction, phosphorus pentachloride (PCl5) reacts with water (H2O) to produce a compound B and hydrochloric acid (HCl).

### Step 2: Determine the product B
From the hydrolysis of PCl5, we know that:
\[ \text{PCl}_5 + \text{H}_2\text{O} \rightarrow \text{POCl}_3 + 2 \text{HCl} \]

Thus, compound B is:
\[ B = \text{POCl}_3 \] (phosphoryl chloride)

### Step 3: Identify the second reaction
The second reaction is:
\[ B + \text{H}_2\text{O} \rightarrow C + \text{HCl} \]

Now, we will substitute B into this reaction:
\[ \text{POCl}_3 + \text{H}_2\text{O} \rightarrow C + \text{HCl} \]

### Step 4: Determine the product C
When POCl3 reacts with water, it undergoes hydrolysis to form:
\[ \text{POCl}_3 + 3 \text{H}_2\text{O} \rightarrow \text{H}_3\text{PO}_4 + 3 \text{HCl} \]

Thus, compound C is:
\[ C = \text{H}_3\text{PO}_4 \] (orthophosphoric acid)

### Step 5: Determine the basicity of compound C
The basicity of a compound refers to the number of hydrogen ions (H+) that can be donated by the compound. In the case of H3PO4, we can analyze its structure:

- H3PO4 has three hydroxyl (OH) groups, each of which can donate one H+ ion.

Therefore, the basicity of compound C (H3PO4) is 3.

### Final Answer
The basicity of compound C (H3PO4) is **3**.

---