Amongst the various ores of a metal (M) (sulphide, carbonates, oxides, hydrated or hydroxides) two ores [X] and [Y] show the following reactivity. (i) [S] on calcination gives a black soil (S), carbon dioxide and water. (ii)[X]Dissolved in dil. HCl on reaction with KI gives a white precipitate(P) and iodine. (ii)[Y] on roasting gives metal (M) and a gas (`G_(1)`) which turns a acidified `K_(2)Cr_(2)O_(7)` solution green. (iv) [Y]on reaction with dil. HCl gives a whitw precipitat (Q) and another gas (`G_(2)`) which turns lead acetate solution black. and also reacts wiht gas `(G_(1))` to precipitate collodial suphur in presence of moisture. The M,S ,[X] and [Y] gives greenish blue flame. The metal ores [X] and [Y] are respectively:
