When a solution of mixture having two inorganic salts was treated with freshly prepared ferrous sulphate in acidic medium, a dark brown ring was formed whereas on treatment with neutral `FeCl_3`,it gave deep red colour which disppeared on boiling and a brown red ppt was formed. The mixture contains

Which one of the following compounds forms a red coloured solution on treatement with neutral FeCl_(3) solution ?

When concentrated sulphuric acid is added slowly to a solution of ferrous sulphate containing nitrate ion, a brown colour ring is formed. The compositionn of the ring is

When 'A' salt solution is added carefully to a saturated solution of Fe(II) sulphate acidified with dilute H_(2)SO_(4) a brown ring is formed at the junction of two liquids. Salt 'A' may be:

An aqueous solution of a mixture of two inorganic salts, when treated with dilute HCl , gave a precipiate (P) and filtrate (Q). The precipitate (P) was found to dissolve in hot water. The filtrate (Q) remained unchanged, when treated with H_(2)S in a dilute mineral acid medium. However, it gave a precipitate (R) With H_(2)S in an ammoniacal medium. The precipitate R gave a coloured solution (S), when treated with H_(2)O_(2) in an aqueous NaOH medium. The coloured solution S contains