7. C4H8O2 The singlet at ppm is in a common location for weakly shifted peaks. What functional group has 2 oxygens and 2 fewer than the maximum number of hydrogens? Note the quartet is quite a ways downfield, and must be coupled to the triplet. 8. C3H8O The insert shows a single peak downfield that disappears when the sample is shaken with D2O. More extended coupling patterns are best analyzed from the outside in, i.e., start with the triplets. Note the location of triplet on the left. And the two triplets can't be coupled to each other, as then nothing could be coupled to the third peak. Also not the the answers to Problems 8&9 are isomers