Answer:
1. There most not be rotation within the molecule.
2. Two non identical group must be present in the double bonded carbon atom.
Step-by-step explanation:
This is because cis/ trans isomerism are that exhibit different structural configurations where the atoms are spartially arranged. They are also refered to as geometric isomers. They cannot be interconverted at room temperature because it requires the bonds to be broken and restructured.
Cis shows that the functional groups on present in the same side which trans isomerism show that the functional groups are on opposite sides.