`A+H_(2)O to B+HCl`
`B+H_(2)O to C+HCl`
Compound (A), (B) and (C) will be respectively:

Options

A. `PCl_(5), POCl_(3), H_(3)PO_(3)`
B. `PCl_(5), POCl_(3), H_(3)PO_(4)`
C. `SOCl_(2), POCl_(3), H_(3)PO_(3)`
D. `PCl_(3), POCl_(3), H_(3)PO_(4)`

Answer

To solve the question, we need to analyze the reactions given and identify the compounds A, B, and C.

### Step-by-Step Solution:

1. **Identify the Reaction of Compound A with Water**:
The first reaction is:
\[ A + H_2O \rightarrow B + HCl \]
This suggests that compound A is a phosphorus-containing compound that reacts with water to produce another phosphorus compound (B) and hydrochloric acid (HCl).

2. **Recognize the Possible Compound for A**:
A common phosphorus compound that reacts with water to produce HCl is phosphorus pentachloride (PCl5). Thus, we can propose:
\[ A = PCl_5 \]

3. **Determine the Product B**:
When PCl5 reacts with water, it produces phosphorus oxychloride (POCl3) and hydrochloric acid:
\[ PCl_5 + H_2O \rightarrow POCl_3 + 2HCl \]
Therefore, we can conclude:
\[ B = POCl_3 \]

4. **Identify the Reaction of Compound B with Water**:
The second reaction is:
\[ B + H_2O \rightarrow C + HCl \]
Here, we need to find out what compound B (POCl3) produces when it reacts with water.

5. **Recognize the Possible Compound for C**:
When phosphorus oxychloride (POCl3) reacts with water, it produces phosphoric acid (H3PO4) and hydrochloric acid:
\[ POCl_3 + 3H_2O \rightarrow H_3PO_4 + 3HCl \]
Thus, we can conclude:
\[ C = H_3PO_4 \]

6. **Summarize the Compounds**:
From the above reactions, we can summarize:
- Compound A is PCl5
- Compound B is POCl3
- Compound C is H3PO4

### Final Answer:
- A = PCl5
- B = POCl3
- C = H3PO4