Rotation about a carbon-carbon double bond does not readily occur because: .1) the overlap of the p orbitals of the carbon-carbon π bond would be lost2) the double bond is much shorter and therefore more difficult to rotate3) the overlap of the sp2 orbitals of the carbon-carbon σ bond would be lost4) the double bond is much stronger and therefore more difficult to rotate

1) The overlap of the p orbitals of the carbon-carbon π bond would be lost

Explanation:

Unlike simple bonds, a double bond can not rotate, since it is not possible to twist the ends of the molecule without breaking the π bond.

In the structure of but-2-ene present in the attachment, we can see the two isomers, cis and trans. These isomers cannot be interconverted by rotation around the carbon-carbon double bond without breaking the π bond.