In `PO_(4)^(3-),P-O` bond order is .

Options

A. `1.25`
B. `2`
C. `-0.75`
D. `-3`

Explanation

To determine the bond order of the P-O bond in the \( \text{PO}_4^{3-} \) ion, we will follow these steps:

### Step 1: Identify the Resonating Structures
The first step is to identify how many resonating structures exist for the \( \text{PO}_4^{3-} \) ion.

- In \( \text{PO}_4^{3-} \), phosphorus (P) is bonded to four oxygen (O) atoms. One of these bonds is a double bond, while the other three are single bonds.
- The negative charges are distributed among the oxygen atoms.

### Step 2: Draw the Resonating Structures
Next, we will draw the possible resonating structures:

1. **Structure 1**: One double bond between P and one O, and three single bonds with the other O atoms.
2. **Structure 2**: The double bond shifts to another O, while one of the single-bonded O atoms takes a negative charge.
3. **Structure 3**: The double bond shifts again, with a different O atom becoming the double-bonded one and another O atom taking a negative charge.
4. **Structure 4**: The last possible structure where the double bond is with the last O atom, and the other three O atoms are single-bonded with negative charges.

This gives us a total of **four resonating structures**.

### Step 3: Count the Sigma and Pi Bonds
Now we need to count the total number of sigma (σ) and pi (π) bonds in one of the resonating structures:

- Each single bond is a sigma bond, and each double bond consists of one sigma bond and one pi bond.
- In one resonating structure, we have:
- 4 sigma bonds (3 single bonds + 1 double bond)
- 1 pi bond (from the double bond)

Thus, the total number of bonds is:
- Total bonds = 4 (σ) + 1 (π) = 5 bonds.

### Step 4: Calculate the Bond Order
The bond order can be calculated using the formula:
\[ \text{Bond Order} = \frac{\text{Total number of bonds}}{\text{Number of resonating structures}} \]
Substituting the values we found:
\[ \text{Bond Order} = \frac{5}{4} = 1.25 \]

### Conclusion
The bond order of the P-O bond in \( \text{PO}_4^{3-} \) is **1.25**.

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