JEE Chemistry 2023 Question with Solution

Given: Resonance in carbonate ion $CO_3^{2-}$ is being asked using the shown three canonical structures.

Find: Which statement correctly describes resonance in $CO_3^{2-}$.

In resonance, the actual molecule or ion is not switching between separate real structures. The true structure is a resonance hybrid of all valid canonical forms. In carbonate ion, the negative charge is delocalized over the three oxygen atoms, so no one structure exists independently.

Therefore:

• Option A is false because resonance forms are not in dynamic equilibrium.
• Option B is false because the forms do not exist separately for different amounts of time.
• Option D is false because individual resonance structures cannot be isolated by physical or chemical methods.
• Option C is correct because $CO_3^{2-}$ has a single actual structure, which is the resonance hybrid of the three structures.

Therefore, the correct option is C.

Given: The carbonate ion $CO_3^{2-}$ is represented by three resonance structures.

Find: The true statement about these structures.

A resonance structure is only a contributing canonical form. The real species is a hybrid with delocalized electrons. Thus, the three drawn structures are not separately existing species.

This means:

1. They are not in dynamic equilibrium with one another.
2. They do not exist individually for equal time.
3. They cannot be identified or isolated individually.
4. The actual carbonate ion is one resonance hybrid structure.

Hence, the correct statement is: $CO_3^{2-}$ has a single structure, the resonance hybrid of the above three structures.

So, the correct option is C.

The answer key conflicts with the solution, and the solution conclusion has been followed.