Which of the following has higher dipole moment and why?
But -1- ene or But -1- yne

Explanation

The direction of dipole moments of individual bonds in 1-butyne and 1-butene are shown below :

The resultant dipole moment of both 1-butyne and 1-butene is due to the dipole moment of `CH_3CH_2C` and C-H bonds which oppose each other . Since a sp carbon is more electronegative than a `sp^2` carbon, therefore, the dipole moment of `CH_3CH_2(sp^3)`-C(sp) bond in 1-butyne is more than that of `CH_3CH_2(sp^3)-C(sp^2)` bond in 1-butene. As a result, the dipole moment of 1-butyne is more than that of 1-butene.