question_answer

What order of \[C-H\] bond lengths do you expect in \[{{C}_{2}}{{H}_{6}},\,{{C}_{2}}{{H}_{4}}\] and \[{{C}_{2}}{{H}_{2}}\] and why?

Answer:

                                                        \[C-H({{C}_{2}}{{H}_{6}})>C-H({{C}_{2}}{{H}_{4}})>C-H({{C}_{2}}{{H}_{2}}).\] This is because hybrid orbitals of carbon involved in overlapping with 1 s orbital of hydrogen are \[s{{p}^{3}},\,s{{p}^{2}}\]  and sp respectively and their sizes are in the order \[s{{p}^{3}}>s{{p}^{2}}>sp\] .