Part 8: STRUCTURE DETERMINATION

The question was set up to try to lead you through the 9 possible constitutional isomers (formerly referred to as structural isomers)  of C₃H₆O, IHD = 1.
Note that since it asked for structural isomers, the stereoisomers (E / Z, R / S) were not considered acceptable.
The isomers and names are shown below.
The equilibrium process that interconverts propanone to 2-propenol and propanal to 1-propenol is TAUTOMERISATION.
The nmr X was that of oxacyclobutane.
The nmr Y was that of propanal. Note the aldehyde H at 9.7ppm and the classic ethyl group coupling pattern (quartet & triplet).
The only compound with a chiral center is propylene oxide (marked * below)