Question

Consider `H_2CO_3 and CO_3^(2-)` ion. Which of the following is correct?
A. There is no resonance in `H_2CO_3`
B. Resonance stabilization energy of `CO_3^(2-)` is more than `H_2CO_3`
C. Resonance stabilization energy of `H_2CO_3` is more than `CO_3^(2-)`
D. There is no resonance in `CO_3^(2-)`

Answer 1

Correct Answer - B
In `CO_3^(2-)` ion the three contributing structures are of equal energy and as such contribute equally toward the resonance hybrid. The three resonating structures of `H_2CO_3` are as follows

Here structures II and III are of higher energy than structure I. Thus, resonance stabilization is less in case of `H_2 CO_3` or resonance stabilization energy of `CO_3^(2-)` ion is more than `H_2CO_3`.