Which compound is not a constitutional isomer of the others?
A)I and II
B)II
C)III
D)IV and V
E)All of these choices are isomers of each other.

Question

Which compound is not a constitutional isomer of the others? 
A)I and II 
B)II 
C)III 
D)IV and V 
E)All of these choices are isomers of each other.

Quizplus · Accepted Answer

Constitutional isomers differ in the order of atoms or connectivity of atoms. In this case, I and II, and IV and V are constitutional isomers because they have the same molecular formula but different connectivity. However, III is not a constitutional isomer because it has a different molecular formula (C4H8O) compared to the other compounds (C4H8O2).

Which Compound Is Not a Constitutional Isomer of the Others