Nature of high resolution proton magnetic resonance spectra:

i) This molecule is expected to give two signals; one for the aromatic protons of the phenyl group and other for the methyl group.

The phenyl protons signal is expected to be in the range of ~ 7.2 ppm and is likely to be a singlet. The methyl group protons are also expected to be a singlet and are expected to be downfield due to the effect of phenyl group. These may appear around δ = 2.3 to 2.6 ppm.

ii) Ethanoic acid is a simple molecule and is expected to give two signals, one for the methyl group and the other for the acidic proton of carboxylic acid. The methyl group protons are expected to appear as a singlet around 2 ppm whereas the acidic protons are likely to be highly downfield in the range of 10-12 ppm.

iii) Methyl isopropyl ketone is slightly more complicated as compared to the above two molecules. The methyl protons are expected to be slightly downfield (~ 2 ppm) as compared to the alkyl protons and would appear as a singlet as these will not couple with other protons. The isopropyl part of the molecule would give two signals. One of these is expected to be a multiplet for one proton. As this proton is close to a carbonyl group, it is likely to appear downfield. The other signal would be for six protons and is expected to appear around 1-2 ppm as a doublet.