In the following questions a statement of Assertion (A) followed by a statement of
Reason (R) is given. Choose the correct option out of the choices given below each question.
Assertion (A): Energy of resonance hybrid is equal to the average of energies of all canonical forms.
Reason (R): Resonance hybrid cannot be presented by a single structure.
(i) Both A and R are correct and R is the correct explanation of A.
(ii) Both A and R are correct but R is not the correct explanation of A.
(iii) Both A and R are not correct.
(iv) A is not correct but R is correct.
A is not correct but R is correct.
We know that the resonance hybrids are always more stable than any of the canonical structures because of the resonance energy.
The energy of orbitals is lowered by the delocalisation of the electrons in resonance, and as the energy is decreased the stability increased, and the amount of energy which is reduced, due to resonance, this energy is called resonance energy.
A canonical structure which is having lower energy,have a greater contribution to resonance hybrid.
Hence, Assertion is not correct but reason is correct.
Option (iv) is correct.