(i) An aqueous solution of a white coloured compound `(A)` on reaction with `HCl` gives a white precipitate of compound `(B)`.
(ii) `(B)` becomes soluble in chlorine water with the formation of `(C)`
(iii) `(C)` reacts with `KI` to give a precipitate which becomes solube in excess of it forming a compount `(D)`. the compound `(D)` is used for detecting ammonium salts.
(iv) `(B)` and `(C)` both, on treatement with `SnCl_(2)` give a grey precipitate of `(E)`.
(v) When conc. `H_(2)SO_(4)` is added slowly into a mixture of cold solutions of `(A)` and `FeSO_(4)` is added slowly into a mixture of cold solutions of `(A)` and `FeSO_(4)`, a brown ring of compound `(F)` is formed.
Compound `(A)` contains ... ions.

Options

A. `Pb^(2+),NO_(3)^(-)`
B. `Hg^(2+)m,NO_(3)^(-)`
C. `Hg_(2)^(2+),NO_(3)^(-)`
D. `Hg^(2+),Cl^(-)`

Explanation

`{:((i),underset((A))(Hg_(2)(NO_(3))_(2))+2HCl tounderset((B))(Hg_(2)Cl_(2))+2HNO_(3)),((ii),Hg_(2)Cl_(2)+Cl_(2)tounderset((C))(2HgCl_(2))" (soluble)"),((iii),HgCl_(2)+2KIto2KCl+HgI_(2)(ppt)),(,HgI_(2)+2KItounderset("used for test of "NH_(3),"Nessler's reagent")underset((D))(K_(2)HgI_(4))),((iv),underset((B))(Hg_(2)Cl_(2))+SnCl_(2)toSnCl_(4)+underset((E)grey)(Hg_(2))),(,2HgCl_(2)+2SnCl_(2)to2SnCl_(4)+underset((E))(Hg_(2))),((v),Hg_(2)(NO_(3))_(2)+2H_(2)SO_(4)to2HgHSO_(4)+2HNO_(3)),(,6FeSO_(4)+2HNO_(3)+3H_(2)SO_(4)to3Fe_(2)(SO_(4))_(3)+4H_(2)O+2NO),(,FesO_(4)+NOtounderset((F)"Brown ring")(FeSO_(4).NO)):}`