Answer:
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.