To determine the bond length between two carbon atoms in a molecule of ethylene C2H4 , we can use the concept of bond order and empirical data from known bond lengths.The bond order of 1.5 in ethylene indicates that the bond between the two carbon atoms is a combination of a single bond and a double bond. The bond length of a single bond C-C is approximately 1.54 angstroms , and the bond length of a double bond C=C is approximately 1.34 .We can use these values to estimate the bond length of the C-C bond in ethylene by taking the average of the single and double bond lengths, weighted by the bond order:Bond length C-C in ethylene = 1.5 * 1.34 + 2 - 1.5 * 1.54 / 2Bond length C-C in ethylene = 2.01 + 0.77 / 2Bond length C-C in ethylene 1.39 So, the bond length between two carbon atoms in a molecule of ethylene C2H4 is approximately 1.39 .