An aqueous solution of a white salt A gives a white precipitate B on treatment with dilute HCl in cold condition. B is soluble in boiling water. An aqueous solution of A gives a yellow precipitate on treatment with a solution of K2CrO4. The soda extract of A is acidified with dilute H2SO4, boiled to remove CO2 and treated with a freshly prepared solution of FeSO4. Concentrated H2SO4 is added to the resulting solution. A brown ring is formed at the junction of the two layers.
The salt A is:
(1) PbBr2
(2) Pb(NO3)2
(3) AgNO3
(4) Hg2(NO3)2