A solution of white solid (A) gave white precipitate (B) with water. On treatment with HCl, the ppt. B produced A. The solution of A gives black precipitate (C ) on reacting with sodium stanite and NaOH. The compound A gives a colourless gas (D) with concentrated `H_(2)SO_(4)` . The gas is soluble in water and its aqueous solution produce with it precipitate with `Hg_(2)(NO_(3))_(2)` but no precipitate with `Hg(NO_(3))_(2)`. Identify (A) to (D) and write the chemical reactions involved.

Explanation

`A=BiCl_(3),B=BiOCl,C=Bi,D=HCl, E=Hg_(2)Cl_(2)`