An aqueous solution of salt (A) gives a white crystalline precipitate (B ) with NaCl solution. The filtrate gives a black precipitate (C ) when `H_(2)S` gas is passed into it. Compound (B) is precipitate (D) with NaI solution and cooling. The compound (A) does not give any gas with dil HCl but liberates a reddish brown gas on heating. Identify the compounds A,B,C and D. Write the chemical equations for varius reactions involved.

Explanation

Aqueous solution of salt (A) gives white precipitate (B) with NaCl and this white precipitate is soluble in hot water hence (B) should be `PbCl_(2).Pb^(2+)` cation is supported that when `H_(2)S` gas is passed in the solution, it gives black precipitate of `PbS.Pb^(2+)` cation is further supported due to the fact that it gives yellow precipitate of `PbI_(2)` with NaI solution. Regarding the anion, since (A) gives reddish brown gas on heating hence the anion should be `NO_(3)^(-)` ion. Therefore the compound (A) is `Pb(NO_(3))_(2)`. The reactions are as follows `:`
`underset((A))(Pb(No_(3))_(2))+2NaCl rarr underset((B))(PbCl_(2)darr)+2NaNO_(3)`
`underset((B))(PbCl_(2))+2NaI rarr underset((C ) "Black")(PbSdarr)+2HCl`
`underset((B))(PbCl_(2))+2NaI rarr underset((D ) "yellow")(PbI_(2)+2NaCl)`
`2Pb(NO_(3))_(2)rarr 2PbO +4NO_(2)uarr +O_(2)uarr`