Question

Arrange the following sresonating structures in decreasing order of stability:

• A. $\left(a\right)>\left(b\right)>\left(c\right)>\left(d\right)$
• B. $\left(d\right)>\left(c\right)>\left(b\right)>\left(a\right)$
• C. $\left(d\right)>\left(b\right)>\left(c\right)>\left(a\right)$
• D. $\left(a\right)>\left(b\right)>\left(d\right)>\left(c\right)$

Answer 1

The correct option is D $\left(a\right)>\left(b\right)>\left(d\right)>\left(c\right)$

Structure $\left(a\right)$ has the maximum number of covalent bonds and least number of charges , so it is the most stable.

Among $\left(b\right),\left(c\right),\left(d\right)$ since all of them have positive charges on nitrogen, on comparing oxygen and carbon.
Structure $\left(b\right)$ has two negative charges on electronegative atom oxygen, so it is more stable than $\left(c\right)\&\left(d\right)$.
Amog, $\left(c\right),\left(d\right)$ like charges are closer to each other in $\left(c\right)$ as compared to $\left(d\right)$.
So $\left(c\right)$ is less stable than $\left(d\right)$ and hence the least stable structure.
Correct order is :
$\left(a\right)>\left(b\right)>\left(d\right)>\left(c\right)$