Question

The energy required to break all the bonds in ethene$\left(C_2{H}_4\right)$ is that of ethyne $\left(C_2{H}_2\right).$

Answer 1

Ethene has a double bond and ethyne has a triple bond.
As the shared electrons in the triple bond are more than the double bond, the energy required to break the double bond in the ethene molecule is less than the energy required to break the triple bond in the ethyne molecule.