Question

Identify the species having one \(\pi\)-bond and maximum number of canonical forms from the following:

• A. SO\(_3\)
• B. O\(_2\)
• C. SO\(_2\)
• D. CO\(_3^{2-}\)

Hint:

The more resonance structures a molecule can have, the more stable it is, as electron density is spread out over the molecule.

Answer 1

The Correct Option is D

Step 1: {Analysis of Canonical Forms} 
Canonical forms are the different resonance structures that a molecule can have, resulting in delocalization of electrons. The species with the maximum number of canonical forms has the most stable resonance structure. 
Step 2: {Analysis of Compounds} 
SO\(_3\) has three resonance structures but lacks a \(\pi\)-bond between sulfur and oxygen in each structure.
O\(_2\) has two resonance structures with a single \(\pi\)-bond between the two oxygen atoms, but it doesn’t have the maximum number of canonical forms.
SO\(_2\) has two resonance structures, but again, it doesn’t maximize the number of canonical forms.
CO\(_3^{2-}\) has three resonance structures, each with a \(\pi\)-bond and delocalized electrons between the carbon and the oxygen atoms. 
The carbonate ion (CO\(_3^{2-}\)) has the maximum number of canonical forms.
Thus, the correct answer is (D).