Question

The pair of species that has the same bond order in the following is :

• A. $CO, NO^+$
• B. $NO^- , CN^-$
• C. $O_2$, $N_2$
• D. $O_2, B_2$

Answer 1

The Correct Option is A

To determine which pair of species has the same bond order, we need to understand what bond order is and how to calculate it for different molecules or ions. Bond order can be given by the equation:

BO = \frac{1}{2} (N_b - N_a)

where N_b is the number of bonding electrons and N_a is the number of antibonding electrons.

Let's calculate the bond order for each of the species:

1. CO :
   Electronic configuration: Similar to N_2,
   Total electrons = 14
   Molecular Orbitals: (\sigma_{1s})^2 (\sigma^*_{1s})^2 (\sigma_{2s})^2 (\sigma^*_{2s})^2 (\pi_{2p})^4 (\sigma_{2p})^2
   N_b = 10, N_a = 4
   Bond Order = \frac{1}{2} (10 - 4) = 3
2. NO^+ :
   Total electrons = 14 (similar to N_2)
   N_b = 10, N_a = 4
   Bond Order = \frac{1}{2}(10 - 4) = 3
3. NO^-, CN^-, O_2, N_2, B_2 :
   For each of these molecules, one needs to follow similar calculation methods of counting bonding and antibonding electrons by considering the number of total electrons or molecular electronic configurations.
   However, through established chemical knowledge and molecular electronic configurations:
   Bond orders are:
   • NO^- : bond order ≈ 1.5
   • CN^-\text{ : bond order = 3}
   • O_2\text{ : bond order = 2}
   • N_2\text{ : bond order = 3}
   • B_2\text{ : bond order = 1}

Based on the calculated bond orders, the pair CO and NO^+ both have a bond order of 3.

Therefore, the correct pair of species with the same bond order is CO, NO^+.