Which of the following have fractional bond order and is(are) paramagnetic ?

Options

A. `C_(2)^(+)`
B. `O_(2)^(-)`
C. `NO`
D. `CO`

Explanation

To determine which of the given species have fractional bond order and are paramagnetic, we will follow these steps:

### Step 1: Identify the Total Number of Electrons
For each species, we need to calculate the total number of electrons present.

1. **C2+**: Each carbon atom has 6 electrons. Therefore, C2 has 12 electrons. Removing one electron for C2+ gives us 11 electrons.
2. **O2-**: Each oxygen atom has 8 electrons. Therefore, O2 has 16 electrons. Adding one electron for O2- gives us 17 electrons.
3. **NO**: Nitrogen has 7 electrons and oxygen has 8 electrons. Therefore, NO has a total of 15 electrons.
4. **CO**: Carbon has 6 electrons and oxygen has 8 electrons. Therefore, CO has a total of 14 electrons.

### Step 2: Determine the Bond Order
Using the trick mentioned in the video transcript, we can find the bond order based on the number of electrons.

1. **C2+ (11 electrons)**:
- The bond order can be calculated as the average of the bond order for 10 electrons (2) and 12 electrons (1).
- Bond Order = (2 + 1) / 2 = 1.5 (fractional bond order).

2. **O2- (17 electrons)**:
- The bond order can be calculated as the average of the bond order for 16 electrons (2) and 18 electrons (1).
- Bond Order = (2 + 1) / 2 = 1.5 (fractional bond order).

3. **NO (15 electrons)**:
- The bond order can be calculated as the average of the bond order for 14 electrons (3) and 16 electrons (2).
- Bond Order = (3 + 2) / 2 = 2.5 (fractional bond order).

4. **CO (14 electrons)**:
- The bond order for 14 electrons is 3 (not fractional).

### Step 3: Check for Paramagnetism
To check if the species are paramagnetic, we need to look for unpaired electrons in their molecular orbital configuration.

1. **C2+**:
- The molecular orbital configuration shows 1 unpaired electron (paramagnetic).

2. **O2-**:
- The molecular orbital configuration shows 1 unpaired electron (paramagnetic).

3. **NO**:
- The molecular orbital configuration shows 1 unpaired electron (paramagnetic).

4. **CO**:
- All electrons are paired (diamagnetic).

### Conclusion
The species that have fractional bond order and are paramagnetic are:
- **C2+**
- **O2-**
- **NO**

### Final Answer
The correct species are **C2+, O2-, and NO**.

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