Question

The bond order of $CO$ and $NO$ is:

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

Answer 1

Answer: (B)

$3$ and $2.5$

$C-O:\sigma 1s^2{\sigma }^{\ast }1s^2\sigma 2s^2{\sigma }^{\ast }2s^2\pi 2P_x^2=\pi 2p_y^2\sigma 2P_y^2$
$Bondorder=\frac{No.ofbondingelectrons\left(10\right)-No.ofelectronsinABMO\left(4\right)}{2}=3$
$N-O:\sigma 1s^2{\sigma }^{\ast }1s^2\sigma 2s^2{\sigma }^{\ast }2s^2\pi 2P_x^2=\pi 2P_z^2\sigma 2P_z^2{\pi }^{\ast }2P_x^1$
$Bondorder=\frac{10-5}{2}=2.5$