Question

The set of species having only fractional bond order values is:

• A. \( C_2^{2-}, N_2, O_2^{2-} \)
• B. \( O_2^+, O_2^-, N_2^+ \)
• C. \( O_2^{2+}, O_2, C_2^{2-} \)
• D. \( Li_2, H_2^-, C_2 \)

Hint:

Fractional bond orders arise in molecular ions where number of electrons is odd or deviates from standard configuration.

Answer 1

The Correct Option is B

Bond order is calculated using: \[ \text{Bond Order} = \frac{1}{2}(n_b - n_a) \] Where \( n_b \) = number of bonding electrons, and \( n_a \) = number of antibonding electrons.
Let’s check: - \( O_2^+ \): BO = 2.5
- \( O_2^- \): BO = 1.5
- \( N_2^+ \): BO = 2.5
All have fractional bond orders.
Other options contain:
- \( N_2 \): BO = 3 (integer)
- \( O_2 \): BO = 2 (integer)
- \( C_2 \): BO = 2 (integer)