A colourless substance 'A' is sparingly soluble in water and gives a water-soluble compound 'B' on treating with a mineral acid. On reacting with and alcoholic potash 'A' produces an obnoxious smell due to the formation of compound 'C'. The reaction of 'A' with benzene sulphonyl chloride gives compound 'D' which is soluble in alkali. With and , 'A' forms compound 'E' which reacts with phenol in alkaline medium to give an orange dye 'F' Identify compounds' A' to 'F'.