The bond order of `CO` and `NO` is .

Options

A. 3 and 2
B. 3 and 2.5
C. 3 and 1.3
D. 3 and 3.5

Answer

To find the bond order of carbon monoxide (CO) and nitric oxide (NO), we will follow these steps:

### Step 1: Determine the total number of electrons
- **Carbon (C)** has 6 electrons.
- **Oxygen (O)** has 8 electrons.
- The total number of electrons in CO = 6 + 8 = **14 electrons**.

### Step 2: Write the molecular orbital configuration for CO
- The molecular orbitals are filled in the following order:
1. σ1s
2. σ*1s
3. σ2s
4. σ*2s
5. σ2p_z
6. π2p_x = π2p_y
7. π*2p_x = π*2p_y

- For 14 electrons, the filling will be:
- σ1s: 2 electrons
- σ*1s: 2 electrons
- σ2s: 2 electrons
- σ*2s: 2 electrons
- σ2p_z: 2 electrons
- π2p_x: 2 electrons
- π2p_y: 2 electrons

- The configuration will be:
- σ1s² σ*1s² σ2s² σ*2s² σ2p_z² π2p_x² π2p_y²

### Step 3: Count the bonding and anti-bonding electrons for CO
- **Bonding electrons**: 2 (σ1s) + 2 (σ2s) + 2 (σ2p_z) + 2 (π2p_x) + 2 (π2p_y) = **10 electrons**
- **Anti-bonding electrons**: 2 (σ*1s) + 2 (σ*2s) = **4 electrons**

### Step 4: Calculate the bond order for CO
- Bond order = 1/2 × (Number of bonding electrons - Number of anti-bonding electrons)
- Bond order for CO = 1/2 × (10 - 4) = 1/2 × 6 = **3**.

### Step 5: Determine the total number of electrons for NO
- **Nitrogen (N)** has 7 electrons.
- **Oxygen (O)** has 8 electrons.
- The total number of electrons in NO = 7 + 8 = **15 electrons**.

### Step 6: Write the molecular orbital configuration for NO
- For 15 electrons, the filling will be:
- σ1s: 2 electrons
- σ*1s: 2 electrons
- σ2s: 2 electrons
- σ*2s: 2 electrons
- σ2p_z: 2 electrons
- π2p_x: 2 electrons
- π2p_y: 2 electrons
- π*2p_x: 1 electron (since we have one extra electron)

- The configuration will be:
- σ1s² σ*1s² σ2s² σ*2s² σ2p_z² π2p_x² π2p_y² π*2p_x¹

### Step 7: Count the bonding and anti-bonding electrons for NO
- **Bonding electrons**: 2 (σ1s) + 2 (σ2s) + 2 (σ2p_z) + 2 (π2p_x) + 2 (π2p_y) = **10 electrons**
- **Anti-bonding electrons**: 2 (σ*1s) + 2 (σ*2s) + 1 (π*2p_x) = **5 electrons**

### Step 8: Calculate the bond order for NO
- Bond order = 1/2 × (Number of bonding electrons - Number of anti-bonding electrons)
- Bond order for NO = 1/2 × (10 - 5) = 1/2 × 5 = **2.5**.

### Final Answer:
- The bond order of CO is **3** and the bond order of NO is **2.5**.