Arrange ehthane, ethylene and acetylene in order of their decreasing C-H bond length. Explain the order.

Explanation

The 1s-orbital of hydrogen overlaps with the `sp^(3),sp^(2)` and sp-hybrid orbitals of carbon in ethane, ethylene and acetylene respectively to form C-H `sigma`-bonds, since the size of three hybrid orbitals decreases I the order `sp^(3) gt sp^(2) gt sp`, the C-H bond length decreases in the order: `C-H(C_(2)H_(6)) gt C-H(C_(2)H_(4)) gt C-H(C_(2)H_(2))`.