Answer: the structures are shown in the image attached.
Explanation:
Before the invention of mordern spectroscopy, Korner's absolute method was commonly applied in determining whether a disubstituted benzene derivative was the ortho, meta, or para isomer. Korner's method depends on the addition of a third group, nitro groups are usually added. The number of isomers formed is then determined. The isomers are usually obtained only in small amounts and analysed to know the structure of the original compound.
