Question

The corect 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. $CO<C{O}_3^{2-}<C{O}_2$

Answer 1

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

Bond length is inversely proportional to bond order and bond order depends on the number of bonds. More is the number of bonds, more is the bond order. $CO$ has triple bond and hence, its bond order is maximum and bond length is minimum. Whereas, $C{O}_2$ has a double bond and so its bond length is greater than $CO$. $C{O}_3^{2-}$ has partial single bond characters due to resonance and so its bond length is maximum.