Question

The correct order of increasing $C-O$ bond lengths in $CO$, $C{O}_3^{2-}$ and $C{O}_2$ is:

• A. $C{O}_3^{2-}$ < $C{O}_2$ < $CO$
• B. $C{O}_2$ < $C{O}_3^{2-}$ < $CO$
• C. $CO$ < $C{O}_3^{2-}$ < $C{O}_2$
• D. $CO$ < $C{O}_2$ < $C{O}_3^{2-}$

Answer 1

The correct option is D $CO$ < $C{O}_2$ < $C{O}_3^{2-}$

Bond length $\propto \frac{1}{Bondorder}$

Bond order of $CO$ = 3 (isoelectronic with $N_2$)

$Bondorder=\frac{No.ofbondsinallpossiblesides}{No.ofresonatingstructures}$

Bond order of $C{O}_2$= $\frac{6}{3}$= 2

Bond order of $C{O}_3^{2-}$= $\frac{4}{3}$= 1.33

So the order of bond length is $CO$ < $C{O}_2$ < $C{O}_3^{2-}$