The correct answer is: C. Ethyne, Ethyne, Ethane.
The length of a carbon bond is inversely proportional to the bond order. The bond order of a carbon-carbon bond is the number of covalent bonds between the two carbon atoms. The bond order of a single bond is 1, the bond order of a double bond is 2, and the bond order of a triple bond is 3.
Ethyne (C2H2) has a triple bond between the two carbon atoms, while ethane (C2H6) has a single bond between the two carbon atoms. Therefore, the carbon-carbon bond in ethyne is shorter than the carbon-carbon bond in ethane.
The order of the compounds in increasing order according to the length of their carbon bond is:
- Ethyne
- Ethane
The other options are incorrect because they do not list the compounds in increasing order according to the length of their carbon bond.