(a) Write two important differences between inductive and resonance effects.

(b) Give reasons to explain the following observations:

(i) Carbon number ‘2’ in CH₃CH₂Cl has more positive charge than that in CH₃CH₂Br.

(ii) CH₃–CH = CH–CH = CH₂ (I) is more stable than CH₃–CH = CH–CH₂–CH = CH₂ (II).

(a)

(b)

(i) Carbon number ‘2’ in CH₃CH₂Cl has more positive charge than that in CH₃CH₂Br because Cl is more electronegative than Br and that’s why C-Cl bond is more polar than C-Br bond. Cl keeps the shared electron pair towards itself as it is more electronegative. So the carbon adjacent to Cl acquires more positive charge s compared to carbon adjacent to Br.

(ii) CH₃–CH = CH–CH = CH₂ (I) is more stable than

CH₃–CH = CH–CH₂–CH = CH₂ (II) because I shows resonance effect whereas there is no conjugation in II. We already know that more the resonating structure more is the stability. I have 2 resonating structures and thus, it is more stable.

CH₃–CH = CH–CH = CH₂ ↔ CH₃=CH - CH=CH - CH₂