Which of the following has the highest value for bond order `-C_(6)H_(6),CO_(3)^(2-) ,NO^(-) and SO_(4)^(2-)` ?

Options

A. `C_6H_6`
B. `CO_3^(2-)`
C. `NO^(-)`
D. `SO_(3)`

Answer

To determine which of the given species has the highest bond order, we will analyze each one: C6H6 (benzene), CO3^(2-) (carbonate ion), NO^(-) (nitroxide ion), and SO4^(2-) (sulfate ion).

### Step-by-Step Solution:

1. **Understanding Bond Order**:
Bond order is defined as the number of bonding pairs of electrons between two atoms. It can be calculated using the formula:
\[ \text{Bond Order} = \frac{\text{Number of bonding electrons} - \text{Number of antibonding electrons}}{2} \]
Alternatively, for resonance structures, the bond order can be determined by the number of bonds divided by the number of resonance structures.

2. **Analyzing C6H6 (Benzene)**:
- Benzene has a structure with alternating single and double bonds, but due to resonance, it is often represented as having a bond order of 1.5 for each C-C bond.
- The resonance structures lead to a bond order of:
\[ \text{Bond Order} = \frac{6 \text{ bonds}}{3 \text{ resonance structures}} = 1.5 \]

3. **Analyzing CO3^(2-) (Carbonate Ion)**:
- The carbonate ion has three resonance structures, and the bond order can be calculated as follows:
- Each C-O bond is equivalent due to resonance, leading to a bond order of:
\[ \text{Bond Order} = \frac{4 \text{ bonds}}{3 \text{ resonance structures}} = \frac{4}{3} \approx 1.33 \]

4. **Analyzing NO^(-) (Nitroxide Ion)**:
- The nitroxide ion has a single bond between nitrogen and oxygen with an additional electron, resulting in a bond order of 2.
- Thus, the bond order for NO^- is:
\[ \text{Bond Order} = 2 \]

5. **Analyzing SO4^(2-) (Sulfate Ion)**:
- The sulfate ion has four resonance structures, and each S-O bond is equivalent due to resonance. The bond order can be calculated as:
\[ \text{Bond Order} = \frac{8 \text{ bonds}}{4 \text{ resonance structures}} = 2 \]

6. **Comparison of Bond Orders**:
- C6H6: Bond Order = 1.5
- CO3^(2-): Bond Order ≈ 1.33
- NO^(-): Bond Order = 2
- SO4^(2-): Bond Order = 2

7. **Conclusion**:
Both NO^(-) and SO4^(2-) have the highest bond order of 2. However, since the question asks for the highest value, we can conclude that both NO^(-) and SO4^(2-) share the highest bond order.

### Final Answer:
NO^(-) and SO4^(2-) have the highest bond order of 2.