NMR spectra for two compounds are given here, together with the molecular formulas. Each compound is a ketone or an aldehyde. In each case, show what characteristics of the spectrum imply the presence of a ketone or an aldehyde, and propose a structure for the compound.
(a)

(b)

200 180 160 140 120 100 80 60 40 20 0 Offset: 40 ppm CDCI (a) CoH1g0 10 0 (ppm) 129 128 (b) 13C NMR spectrum CHI (CH) of CgHg (CH) 133 CH3) 26 145 197 200 180 160 140 120 100 80 60 40 20 o (ppm)