in spectrum f, search for the signals associated with fragments iii-iv and label each signal accordingly, using the same notation from the starting material. for example, proton hc from 2-acetylpyridine would correlate to fragment iii hc in the addition product and proton hc from 4-nitrobenzaldehyde would correlate to fragment iv hc in the addition product. note that the actual chemical shifts may deviate slightly from spectra a and b but the shapes and relative shifts will be similar.