In qualitative analysis when H2S is passed through an aqueous solution of salt acidified with dil. HCl, a black precipitate is obtained. On boiling the precipitate with dil. HNO3, it forms a solution of blue colour. Addition of excess of aqueous solution of ammonia to this solution gives _________.
(i) deep blue precipitate of Cu (OH)2
(ii) deep blue solution of [Cu (NH3)4]2+
(iii) deep blue solution of Cu(NO3)2
(iv) deep blue solution of Cu(OH)2.Cu(NO3)2
