(b)distinguishes cis-butadiene and trans butadiene
(c)distinguishes cyclobutadiene cis-butadiene
(d)has different coulomb integrals for non equivalent carbons
Answer
Answer: C ✓ checked by 4AB · confidence high
The source book printed no answer; this one was worked out and checked — see the explanation.
Explanation
Hückel theory uses connectivity only: it ignores electron repulsion, gives all carbons the same α, cannot tell cis- from trans-butadiene, but does distinguish cyclobutadiene (extra bond) from butadiene.