`P_(4)O_(10)` on reactig with water does not form

Options

A. Tetra metaphosphoric acid
B. Phorsphorous acid
C. Orthophosphoric acid
D. Pyrphosphoric acid

Answer

To solve the question regarding what `P4O10` does not form when reacting with water, we can follow these steps:

### Step 1: Understand the Reaction of `P4O10` with Water
`P4O10` (tetraphosphorus decoxide) is known to react with water. The products of this reaction depend on the conditions (temperature) under which the reaction occurs.

### Step 2: Identify the Products of the Reaction
1. **Cold Water Reaction**: When `P4O10` reacts with cold water, it forms meta-phosphoric acid (`HPO3`), which can be represented as:
\[ P4O10 + 4H2O \rightarrow 4HPO3 \]
2. **Hot Water Reaction**: When `P4O10` reacts with hot water, it forms phosphoric acid (`H3PO4`), represented as:
\[ P4O10 + 6H2O \rightarrow 4H3PO4 \]

### Step 3: Analyze the Options Given
The options provided are:
- Tetramethyl phosphoric acid
- Phosphorus acid
- Orthophosphoric acid
- Pyrophosphoric acid

### Step 4: Determine Which Compound is Not Formed
From the reactions identified:
- `P4O10` does not produce pyrophosphoric acid (`H4P2O7`) when reacting with water. Instead, it produces meta-phosphoric acid or phosphoric acid depending on the temperature of the water used.

### Conclusion
Thus, the correct answer to the question "P4O10 on reacting with water does not form" is **pyrophosphoric acid**.

### Final Answer
**Pyrophosphoric acid**

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