Which of the following statement is not valid for oxoacids of phosphorus?

Options

A. Orthophosphoric acid is used in the manufacture of triple superphosphate
B. Hypophousphorus acid is a diprotic acid
C. All oxoacids contain tetrahedral four coordinated phosphorus
D. All oxoacids contain at least one `P=O` unit and one `P-OH` group.

Explanation

To determine which statement is not valid for oxoacids of phosphorus, let's analyze each statement systematically.

### Step 1: Analyze the first statement
**Statement:** Orthophosphoric acid is used in the manufacture of triple superphosphate.
**Analysis:** This statement is true. Orthophosphoric acid (H₃PO₄) is indeed used in the production of fertilizers, including triple superphosphate.

### Step 2: Analyze the second statement
**Statement:** Hypophosphorus acid is a diprotic acid.
**Analysis:** This statement is false. Hypophosphorus acid has the formula H₃PO₂. Its structure allows it to donate only one proton (H⁺) in aqueous solution, making it a monoprotic acid, not diprotic.

### Step 3: Analyze the third statement
**Statement:** All oxoacids contain tetrahedral 4 coordinated phosphorus.
**Analysis:** This statement is true. In oxoacids of phosphorus, phosphorus typically exhibits a tetrahedral coordination due to its ability to form four bonds.

### Step 4: Analyze the fourth statement
**Statement:** All oxoacids contain at least one P-O-O unit and one P-OH group.
**Analysis:** This statement is true. In oxoacids like hypophosphorus acid (H₃PO₂), there is at least one P-O bond and one P-OH group present.

### Conclusion
After analyzing all the statements, the one that is not valid is:
**Hypophosphorus acid is a diprotic acid.** This is incorrect because hypophosphorus acid is a monoprotic acid.

### Final Answer
**The statement that is not valid for oxoacids of phosphorus is: Hypophosphorus acid is a diprotic acid.**

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