See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Step-by-Step Solution **Structure Analysis:** The molecule shows: - C1=C2 (double bond) - C2-C3 (single bond) - C3=C4 (double bond) This is a conjugated diene system with resonance stabilization. **Resonance Effect:** Due to conjugation, the electrons in the $\pi$ bonds delocalize. The C1–C2 and C3–C4 double bonds gain some single bond character, while the C2–C3 single bond gains some double bond character: $$\text{C1=C2-C3=C4} \leftrightarrow \text{C1-C2=C3-C4}$$ **Bond Length Comparison:** - **C1–C2 bond:** Double bond weakened by resonance → longer than typical C=C - **C3–C4 bond:** Double bond weakened by resonance → longer than typical C=C - **C2–C3 bond:** Single bond strengthened by resonance → shorter than typical C–C **Conclusion:** C1–C2 (partial double bond) is **shorter** than C3–C4 (also partial double bond) because C1–C2 experiences stronger conjugation effects due to its position in the diene system. **Answer: (B)** C1–C2 bond is shorter than C3–C4 bond ✓