• # question_answer An aromatic compounds among other things should have a $\pi$-electron cloud containing electrons where $n$ can't be [J & K 2005] A) 1/2 B) 3 C) 2 D) 1

According to Huckel ruel, all aromatic compounds must have $(4n+2)\pi$electrons where $n$ is an integer, i.e., $n=0,\,1,\,2,\,3,\,...$ and possesses unusual stability due to the complete delocalisation of $\pi$-electrons.