The structure of ortho-phosphoric acid is:

Options

A. `O larr overset(H)overset(|)underset(H)underset(|)P-OH`
B. `H-O-underset(O)underset(darr)P=O`
C. `H-O-underset(H)underset(|)underset(O)underset(|)overset(O)overset(uarr)P-OH`
D. `Olarrunderset(H)underset(|)underset(O)underset(|)overset(H)overset(|)P-OH`

Answer

To determine the structure of ortho-phosphoric acid (H₃PO₄), we can follow these steps:

### Step 1: Identify the Chemical Formula
The chemical formula for ortho-phosphoric acid is H₃PO₄. This indicates that the compound contains three hydrogen atoms, one phosphorus atom, and four oxygen atoms.

**Hint:** Remember that the subscripts in the chemical formula indicate the number of each type of atom present in the molecule.

### Step 2: Understand the Nature of the Acid
Ortho-phosphoric acid is classified as a weak acid. It is important to note that it contains three acidic hydrogen atoms that can dissociate in solution.

**Hint:** Weak acids do not completely dissociate in water, which is a key characteristic to remember when studying acids.

### Step 3: Draw the Central Phosphorus Atom
Start by placing the phosphorus atom (P) at the center of the structure. Phosphorus is the central atom in ortho-phosphoric acid.

**Hint:** Central atoms in molecular structures often have multiple bonds or are surrounded by other atoms.

### Step 4: Attach Oxygen Atoms
Attach four oxygen atoms (O) to the phosphorus atom. One of these oxygen atoms will be connected through a double bond, while the other three will be connected through single bonds.

**Hint:** Double bonds can be represented by two lines between atoms, while single bonds are represented by one line.

### Step 5: Attach Hydrogen Atoms
Attach three hydrogen atoms (H) to the three oxygen atoms that are connected by single bonds. These hydrogen atoms represent the acidic protons of the acid.

**Hint:** Each hydrogen atom will typically bond to an oxygen atom, forming hydroxyl groups (-OH).

### Step 6: Finalize the Structure
The final structure of ortho-phosphoric acid will consist of a phosphorus atom double-bonded to one oxygen atom and single-bonded to three other oxygen atoms, each of which is bonded to a hydrogen atom.

**Hint:** Visualizing the three-dimensional arrangement can help in understanding the molecular geometry.

### Conclusion
The correct structure of ortho-phosphoric acid (H₃PO₄) can be represented as follows:

```
O
||
H - O - P - O - H
|
O - H
```