• # question_answer Decreasing order of C-C bond length is [JEE Orissa 2004] ${{C}_{2}}{{H}_{4}}$ ${{C}_{2}}{{H}_{2}}$ ${{C}_{6}}{{H}_{6}}$ ${{C}_{2}}{{H}_{6}}$ A) IV > III > I > II B) I > II > IV > III C) II > I > IV > III D) IV > I > III > II

Bond length $\propto \frac{1}{\text{Bond order}}$            Bond order = $\frac{\text{Bonding -- antibonding electron}}{\text{2}}$ Bond order is highest for ${{C}_{2}}{{H}_{6}}$ so it has minimum bond strength.