To determine if a molecule exhibits positional isomerism or functional isomerism, one must examine the molecular structure and the arrangement of functional groups within the molecule. 1. Positional Isomerism: Positional isomers occur when the molecular formula is the same, but the position of the functional group or substituent differs within the molecule. To identify positional isomers, look for molecules with the same molecular formula and functional groups but with different positions of the functional groups on the carbon chain.Example: - 1-Propanol CH3CH2CH2OH and 2-Propanol CH3CH OH CH3 are positional isomers. Both have the same molecular formula C3H8O and contain an alcohol functional group -OH . However, the position of the -OH group differs: it is attached to the first carbon in 1-propanol and the second carbon in 2-propanol.2. Functional Isomerism: Functional isomers have the same molecular formula but different functional groups. To identify functional isomers, look for molecules with the same molecular formula but with different types of functional groups or different connectivity of atoms.Example:- Ethyl ether CH3CH2OCH3 and ethanol CH3CH2OH are functional isomers. Both have the same molecular formula C2H6O , but they have different functional groups: ethyl ether has an ether functional group C-O-C , while ethanol has an alcohol functional group -OH .In summary, to determine if a molecule exhibits positional or functional isomerism, examine the molecular structure and the arrangement of functional groups. Positional isomers have the same molecular formula and functional groups but differ in the position of the functional groups, while functional isomers have the same molecular formula but different functional groups.