Final answer:
Molecules with the formulas CH3CH₂COOH and C3H6O₂ could not be structural isomers.
Step-by-step explanation:
The statement 'Molecules with the formulas CH3CH₂COOH and C3H6O₂ could be structural isomers' is false.
Structural isomers are molecules with the same molecular formula but different structural arrangements. In this case, CH3CH₂COOH represents propanoic acid, while C3H6O₂ represents propanoic anhydride. These compounds have different functional groups and cannot be structural isomers.