Explain the following : i) Lead (Pb^(2+)) is placed in the first as well as second group of qualitative analysis. ii) The colour of mercurous chloride, Hg_(2),Cl_(2), changes from white to black when treated with ammonia. iii) During the qualitative analysis of a mixture containing Cu^(2+) and Zn^(2+) ions, H_(2)S gas is passed through an acidified solution containing these ions in order to test Cu^(2+) alone. Explain briefly.

Give reason for, ''The colour of mercurous chloride, Hg_(2)Cl_(2) , changes from white to black when treated with ammonia.''

Colour of cobalt chloride solution is

Which liberates ammonia when treated with

Colour of cobalt chloride solution is:

Colour of cobalt chloride solution is:

Mercurous chloride turns black on treatment with ammonium hydroxide. This is due to the formation of