A yellow solid (A) is unaffected by acids and bases. It is not soluble in water. It dissolves slowly in hot conc. HNO3 and a brown gas (B) is released. The solid (A) dissolves only in a boiling solution of sodium sulphite giving a clear solution (C). Acidification (C) causes a colourless gas (D) to be liberated, accompanied by an appearance of a milky ppt. (E) in the solution. Identify (A) to (E).
