Chemistry - STEREO ISOMERISM Question with Solution | TestHub

Compound (I) is butan-2-one (a ketone) and compound (II) is 2-methylpropanal (an aldehyde). Compounds (III) and (IV) are the two geometrical (E/Z) enol forms of (I), not of (II); the enol of (II) would be 2-methylprop-1-en-1-ol. (I) and (II) are constitutional isomers (ketone vs aldehyde), not tautomers, and they give different enols. (II) and the enols (III), (IV) have the same molecular formula C₄H₈O but different functional groups (aldehyde vs enol), so they are functional isomers.

Ans. (C)