The strongest bond strength is of HCCH (Ethyne), then comes H₂CCH₂ (Ethene) and H₃CCH₃ (Ethane) has the least bond strength as compare to Ethyne and Ethene.
HCCH > H₂CCH₂ > H₃CCH₃ Strongest ----------------------------------------------> Weakest Explanation: Ethyne has triple bond, one sigma bond and two pi bonds, Hence, a greater overlap is found between two carbon atoms which resulted in shortening the bond length (i.e 1.9 Angstrome). Also carbon carbon triple bond has highest force constant value i.e 15 ×10⁵ dyne/cm which is greater than carbon carbon double bond (10 ×10⁵ dyne/cm) and single bond (5 × 10⁵ dyne/cm).
