Question

What is the correct order of increasing $C - O$ bond length of $CO , CO _3^{2-}$ and $CO _2 ?$

• A. $CO_{3}^{2 -} < CO_{2} < CO$
• B. $CO_{2} < CO_{3}^{2 -} < CO$
• C. $CO < CO_{3}^{2 -} < CO_{2}$
• D. $CO < CO_{2} < CO_{3}^{2 -}$

Answer 1

Answer: (D)

Carbon monoxide $14$ electrons containing molecule. According to molecular orbital theory its bond order =$3$
$inCO_{3}^{2 -}$
$Bondorder=\frac{\text{Total number of bonds in the molecule}}{\text{Number of resonating structures}}$

$lnCO_{2};O=C=O;$ Bond order =$2$
Bond length $ \propto \frac{1}{\text{ Bond order }}$