How many of the following substances/molecules/ion have bond order 1.33 ?
`BF_(3)`, Boron nitride, graphite,
`NO_(3)^(-), SO_(3)^(2-), SO_(4)^(2-), PO_(4)^(3-)`

Answer

To determine how many of the given substances have a bond order of 1.33, we will analyze each substance one by one.

### Step 1: Analyze BF₃ (Boron Trifluoride)
- **Structure**: BF₃ has three sigma bonds (B-F) and one pi bond (due to back donation from F).
- **Calculation**:
- Total bonds = 3 (sigma) + 1 (pi) = 4
- Number of atoms = 3 (B and 3 F)
- Bond order = Total bonds / Number of atoms = 4 / 3 = 1.33

### Step 2: Analyze Boron Nitride
- **Structure**: Boron nitride has a similar structure to graphite, where each boron atom is bonded to three nitrogen atoms.
- **Calculation**:
- Total bonds = 3 (sigma) + 1 (pi) = 4
- Number of atoms = 4 (1 B and 3 N)
- Bond order = 4 / 3 = 1.33

### Step 3: Analyze Graphite
- **Structure**: Graphite consists of layers of carbon atoms bonded in a hexagonal lattice, with each carbon bonded to three others.
- **Calculation**:
- Total bonds = 3 (sigma) + 1 (pi) = 4
- Number of atoms = 4 (1 C and 3 other C)
- Bond order = 4 / 3 = 1.33

### Step 4: Analyze NO₃⁻ (Nitrate Ion)
- **Structure**: The nitrate ion has one nitrogen atom bonded to three oxygen atoms, with resonance structures showing one double bond and two single bonds.
- **Calculation**:
- Total bonds = 3 (sigma) + 1 (pi) = 4
- Number of atoms = 4 (1 N and 3 O)
- Bond order = 4 / 3 = 1.33

### Step 5: Analyze SO₃²⁻ (Sulfite Ion)
- **Structure**: The sulfite ion has one sulfur atom bonded to three oxygen atoms, with one double bond and two single bonds.
- **Calculation**:
- Total bonds = 3 (sigma) + 1 (pi) = 4
- Number of atoms = 4 (1 S and 3 O)
- Bond order = 4 / 3 = 1.33

### Step 6: Analyze SO₄²⁻ (Sulfate Ion)
- **Structure**: The sulfate ion has one sulfur atom bonded to four oxygen atoms, with two double bonds and two single bonds.
- **Calculation**:
- Total bonds = 4 (sigma) + 2 (pi) = 6
- Number of atoms = 5 (1 S and 4 O)
- Bond order = 6 / 4 = 1.5 (not 1.33)

### Step 7: Analyze PO₄³⁻ (Phosphate Ion)
- **Structure**: The phosphate ion has one phosphorus atom bonded to four oxygen atoms, with one double bond and three single bonds.
- **Calculation**:
- Total bonds = 4 (sigma) + 1 (pi) = 5
- Number of atoms = 5 (1 P and 4 O)
- Bond order = 5 / 4 = 1.25 (not 1.33)

### Conclusion
Now, we count how many substances have a bond order of 1.33:
- BF₃: 1.33
- Boron Nitride: 1.33
- Graphite: 1.33
- NO₃⁻: 1.33
- SO₃²⁻: 1.33
- SO₄²⁻: 1.5 (not counted)
- PO₄³⁻: 1.25 (not counted)

**Total substances with bond order 1.33 = 5**

### Final Answer
**5 substances have a bond order of 1.33.**

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