(i) A blue coloured compoud (A) on heating gives two products, (B) and (C).
(ii) A metal (D) is deposited on passing hydrogen through heated (B).
(iii) The solution of (B) in HCl on treatment with gives a choclate brown coloured precipitated of compound (E).
(iv) (C) turns lime water milky which disappears on continous passage of (C) forming a compound (F).
Identify (A) to (F) and give chemical equations for the reactions at steps (i) to (iv).