Question

Which one of the following pairs of species have the same bond order?

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

Answer 1

The correct option is B ${CN}^{-}$, $CO$

The trick here is to calculate the number of electrons in each species. The traditional way is to use M.O.T and it is the most rigorous way.

$O_2$ has 16 electrons and ${NO}^{+}$ has 14 electrons.

${CN}^{-}$ has 14 electrons and $CO$ has 14 electrons.

$N_2$ has 14 electrons and $O_2$ has 17 electrons.

$CO$ has 14 electrons and $NO$ has 15 electrons.

Since we know only 1 option is correct, we can clearly go for the second one.