Question

The increasing order of bond order of $O_2, O_2^+ , O_2^-$ and $O_2^{-}$ is

• A. $O _{2}^{+}, O _{2}, O _{2}^{-}, O _{2}^{--}$
• B. $O _{2}^{--}, O _{2}^-, O _{2}^{+}, O _{2}$
• C. $O _{2}, O _{2}^{+}, O _{2}^{-}, O _{2}^{--}$
• D. $O _{2}^{2-}, O _{2}^{-}, O _{2}, O _{2}^{+}$

Answer 1

Answer: (D)

According to MOT bond order is given by the formula:
B.O. $=\frac{ N _{ B }- N _{ A }}{2}$ where $N _{ A }, N _{ B }$ are the number of electrons in antibonding and bonding molecular orbital respectively,
Bond order for $O _{2}=\frac{10-6}{2}=2$
Bond order for $O _{2}^{+}=\frac{10-5}{2}=2.5$
Bond order for $O _{2}^{-}=\frac{10-7}{2}=1.5$
Bond order for $O _{2}^{2-}=\frac{10-8}{2}=1$