Which of the following statements is /are true ?

Options

A. `Ag^(+)` ions do not give white precipitate with concentrated `HCI`.
B. `Cu^(2+)` ions produce a white precipitate when KCN solution is added in a small quantity
C. `Hg^(2+)` ions give deep blue precipitate with cobalt acetate and ammonium thiocyanate
D. Black precipitate of `BiI_(3)` turns orange when heated with water.

Answer

A, B, C, D

Explanation

(a) `Na_(2)S rarr H_(2)S`
(b) `S^(2-) rarr S darr`
(c) `S^(2-) rarr Na_(4) [Fe(CN)_(5)NOS]`
(d) `SO_(4)^(2-) rarr CaSO_(4)darr` while `S^(2-)rarr CaS` (soluble)