(i)A black coloured compound (B) is formed on passing H_(2)S through the solution of a compound (A) in NH_(4)OH (ii)(B) on treatment with HCl and potassium chlorate or aquaregia gives (A) (iii)(A) on treatment with KCN gives a buff/reddish-brown coloured precipitate which dissolves in excess of this reagent forming a compound ( C). (iv)The compound ( C) is changed into a compound (D) when its aqueous solution is boiled in air. (v)The solution of (A) was treated with excess of NaHCO_(3) & then with bromine water. On cooling & shaking for some time, a green colour of compound (E) is formed.No change is observed on heating. Identify (A) to (E) and give chemical equations.

(i)A black coloured compound (B) is formed on passing H_(2)S through t

1.	(i)A black coloured compound (B) is formed on passing H_(2)S through the solution of a compound (A) in NH_(4)OH (ii)(B) on treatment with HCl and potassium chlorate or aquaregia gives (A) (iii)(A) on treatment with KCN gives a buff/reddish-brown coloured precipitate which dissolves in excess of this reagent forming a compound ( C). (iv)The compound ( C) is changed into a compound (D) when its aqueous solution is boiled in air. (v)The solution of (A) was treated with excess of NaHCO_(3) & then with bromine water. On cooling & shaking for some time, a green colour of compound (E) is formed.No change is observed on heating. Identify (A) to (E) and give chemical equations.
Answer» Solution :(i)`Co_(2+) + S^(2-) overset (NH_(4)OH//NH_(4)Cl) to CoS DARR` (black) (ii)`CoS darr + HNO_(3)+ 3HCl to Co^(2+) +S darr + NOCL uarr + 2Cl^(-) + 2H_(2)O` (III)`Co^(2+) + 2CN^(-) to Co(CN)_(3) darr` (reddish-brown) `Co(CN)_(2) darr + 4CN^(-) to 4[Co(CN)_(6)]^(4-)`(brown solution) (iv)`4[Co(CN)_(6)]^(4-) + H_(2)O + O_(2) to 4[Co(CN)_(6)]^(3-)` (yellow solution)+`4OH^(-)` (v)`Co^(2+) + 6HCO_(3)^(-) to [Co(CO_(3))_(3)]^(4-) + 3H_(2)O + 3CO_(2)` `[Co(CO_(3))_(3)]^(4-) overset([O])to[Co(CO_(3))_(3)]^(3-)` (green solution)