question_answer

Match the items given below in column I with those in column II and choose the correct option given below.

	Column I (Compound)		Column II (Characteristics)
I.	[10]-Annulene	P.	Anti-aromatic
II.	[6] - Annulene	Q.	Non-aromatic
III.	[18]-Annulene	R.	Aromatic
IV.	Cyclohepta-1,3,5-trienyl anion	S.	Undergo SE (substitution by electrophile) reactions

Options:

A) I - R and S      II - Q              III - P               IV - Q

B) I - Q                II - R and S       III - Q          IV - P

C) I - P                II - Q              III - R               IV - S

D) I - S                II - P              III - R               IV - Q

Correct Answer: B

Solution :

[b] (I) \[10\pi {{e}^{-'}}s\] in resonance. Should be aromatic. But due to repulsion between interior H-atoms ring is non planar and hence is non-aromatic. (II) \[6\pi {{e}^{-}}s\] in resonance. Aromatic (III) [18] Annulene: \[18\pi {{e}^{-'}}s\] in resonance but due to repulsion between interior H-atoms ring is non- planar. and is non- aromatic. (IV)  \[8\pi {{e}^{-'}}s\] in resonance and is antiaromatic.