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 $O_2^{2-}=\frac{10-8}{2}=1$