(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
Explanation
Simple Hückel theory uses only connectivity: it ignores electron repulsion, gives every carbon the same α, and cannot tell cis- from trans-butadiene. It does distinguish cyclobutadiene from butadiene because the ring has an extra C–C bond (different secular determinant).