A scarlet compound A is treated with conc. HNO3 to give a chocolate brown precipitate B. The precipitate is filtered and the filtrate is neutralised with NaOH. Addition of KI to the resulting solution gives a yellow ppt. C. The brown ppt" B on warming with conc. HNO3 in the presence of Mn(NO3)2 produces a pink coloured solution due to the formation of D. Identify A,B, C and D. Write the reaction sequence.
