Question

According to molecular orbital theory, the total number of bonding electron pairs in $O_2$ is:

• A. $2$
• B. $3$
• C. $5$
• D. $4$

Answer 1

The correct option is C $5$

Electronic configuration of $O_2$ is determined as follows;

$O_2:$ $\left(\sigma 1s{)}^2\right({\sigma }^{\ast }1s{)}^2\left(\sigma 2s{)}^2\right({\sigma }^{\ast }2s{)}^2\left(\sigma 2p{)}^2\right(\pi 2p{)}^4({\pi }^{\ast }2p{)}^2$

Bond order $=\frac{1}{2}(10–6)=2;$ double bond $O=O.$

The total number of bonding electron pairs is 5 as there are 10 electrons.