With an aqueous solution containing Cu(I) ions complexed by ammonia, isomer P gave a red precipitate. On vigorous oxidation by aqueous manganate (VII) ions, isomer Q gave only ethanoic acid whereas isomer R gave an unbranched chain, dicarboxylic acid. Write structual formulae for isomers P, Q and R: explain your reasoning. This is a past old examination question, I'm finding this difficult to answer. Anyone have any ideas?