Answer:
To be enantiomers, a molecule must have at least three different atoms or groups connected to a central carbon.
Explanation:
To be structural isomers, the molecules must have the same formula and different structure, it means, the same number of each element. CH3CH2COOH and C3H6O2 have 3C, 6H, and 2O, so they can be structural isomers.
Cis-trans isomers occur in molecules with a double bond between carbons, and each carbon has to have 2 different atoms or groups connected to it.
Enantiomers are optic isomers, and to occur, the molecule has to have a chiral carbon (an asymmetric carbon), which is a central carbon connected to four different atoms or groups. So the third affirmative is false because it says that is necessary only three different atoms or groups connected to a central carbon.
