Question

Which of the following ring compounds obeys Huckel's rule?

• A. $C_4{H}_4^{-1}$
• B. $C_4{H}_4^{+1}$
• C. $C_4{H}_4^{-2}$
• D. $C_4{H}_4$

Answer 1

The correct option is A $C_4{H}_4^{-1}$

huckel's rule (4n + 2 rule) : This rule defines that in order to be aromatic a molecule should have a certain number of $\pi$ electrons ($\pi$ bonds or lone pair or lone pairs within p orbitals ) within a closed loop of parallel adjacent p- orbitals in this 4n+2$\pi$ electrons where $n=0,1,2,3$ and so on.
therefore in $C_4{H}_4^{-1}$. $4n+2\pi$ electrons . therefore Huckel's rule is obeyed