A green ore (A) of a metal present as a double /mixed compound is treated with HCl and then H_(2)S is passed in the solution. A back precipitate (B) is obtained, that is insoluble in yellow ammonium sulphide. The precipitate is dissolved in HNO_(3) and then excess of NH_(4)OH is added. The solution becomes coloured but this colour is discharged upon addition of KCN in excess due to the formation of compound (C). The solution of (A) in H_(2)O liberates a colourless and odourless gas on reaction with dilute H_(2)SO_(4) and solution of (A) gives white precipitate on addition of BaCl_(2) solution. The procedure used to estimate the metal ion of ore (A) gravimetrically, is ?

A green ore (A) of a metal present as a double /mixed compound is trea

1.	A green ore (A) of a metal present as a double /mixed compound is treated with HCl and then H_(2)S is passed in the solution. A back precipitate (B) is obtained, that is insoluble in yellow ammonium sulphide. The precipitate is dissolved in HNO_(3) and then excess of NH_(4)OH is added. The solution becomes coloured but this colour is discharged upon addition of KCN in excess due to the formation of compound (C). The solution of (A) in H_(2)O liberates a colourless and odourless gas on reaction with dilute H_(2)SO_(4) and solution of (A) gives white precipitate on addition of BaCl_(2) solution. The procedure used to estimate the metal ion of ore (A) gravimetrically, is ?
Answer» Treatement of ore with excess KCN Treatement of solution of ore with AG METAL. Treatement of ore with excessammonia Treatement of ore with excess KSCN. Answer :D