An aqueous solution of salt (A) gives a give a white precipitate ( B) with sodium chloride solution . Compound ( B) dissolves in hot water and the solution on treatment with sodium iodide give a yellow precipitate ( D) ,. and on passing ` H_2 S` through solution ( B) gives a black ppt . (C) . Compound (A) does not give any gas with dil `HCl`, but liberates a reddish brown gas on heating identify compounds (A), (B), ( C) , and (D) .

Explanation

Salt (A) on heating libreates reddish brown gas , hence, it contains nitrate.
(B) dissolves in hot water and gives a yellow ppt. with Nal , hence , it is `PbCl_(2)` and slt (A) is `Pb(NO_(3)_(2)`.
Pbunderset((A))(NO_(3)_(2(aq)))+2 Na Cl_((aq)) rarrunderset((B))underset("White ppt")(PbCl_(2)darr)+2NaNO_(3(aq))`
2Pn(NO_(3))_(2)overset(Delta)(rarr)2PbO+underset((B))underset(Reddish brown)(2NO_(2)uarr)+3Ouarr`
`underset((B))underset("White ppt")(Pb(nO_(3))_(2))overset(Hot water)(rarr)Pb_((aq))^(2+)+2Cl_((aq))^(Θ)`
`PbCl_(2(qa)) +2Nal rarr 2Nal rarr 2NaCl+ underset("Yellow ppt.(D)")(Pbl_(2)darr)`
`PbCl_(2(aq)) +H_(2)S rarr underset ("Black ppt. (C)")(PbSdarr+2HCl)`
Hebnce, (A) is `Pb(NO_(3))_(2)`, lead chloride
(B) is `PbCl_(2)`, lead chloride
(C) is `PbS`, lead sulphide
(D) is `Pbl_(2)`, lead iodide.