Orthophosphoric acid `underset(220^(@)C)overset("gentle heat") to X`
what is/are correct about X?

Options

A. It is a tetrabasic acid
B. It contains one P-O-P bond
C. it is a dibasic acid
D. On hydrolysis it produces metaphosphoric aciid

Explanation

To solve the question regarding the thermal decomposition of orthophosphoric acid (H₃PO₄) at 220°C, we will follow these steps:

### Step 1: Identify the product formed from orthophosphoric acid.
When orthophosphoric acid is subjected to gentle heat at 220°C, it undergoes dehydration to form pyrophosphoric acid (H₄P₂O₇) and water (H₂O). The balanced chemical equation for this reaction is:

\[ 2 H₃PO₄ \rightarrow H₄P₂O₇ + H₂O \]

### Step 2: Analyze the properties of pyrophosphoric acid (X).
Now that we know the product X is pyrophosphoric acid, we need to evaluate the statements given in the question regarding its properties.

### Step 3: Evaluate each statement about pyrophosphoric acid (X).

1. **Statement A: It is a tetrabasic acid.**
- Pyrophosphoric acid has four replaceable hydrogen atoms (from the four hydroxyl groups). Therefore, it is indeed a tetrabasic acid. **(True)**

2. **Statement B: It contains one POP bond.**
- The structure of pyrophosphoric acid includes a P-O-P bond, confirming that it contains one POP bond. **(True)**

3. **Statement C: It is a dibasic acid.**
- Since pyrophosphoric acid has four replaceable hydrogen atoms, it cannot be classified as a dibasic acid. **(False)**

4. **Statement D: On hydrolysis, it produces metaphosphoric acid.**
- Upon hydrolysis, pyrophosphoric acid reverts to orthophosphoric acid, not metaphosphoric acid. **(False)**

### Conclusion:
The correct statements about product X (pyrophosphoric acid) are:
- A: It is a tetrabasic acid.
- B: It contains one POP bond.