Compound (A) is greenish solid which gives the following tests `:` (i) Addition of `BaCl_(2)` solution to a solution of (A) results in the formation of a white precipitate (B) which is insoluble in dilute HCl . (ii) On heating water vapours and two oxides of sulphur (C ) & (D) are liberated,leaving a red brown residue (E ). (iii) Compound (E) dissolves in warm concentrated HCl to give a yellow solution (F). (iv) With `H_(2)S` gas, the solution (F) yields a yellow white precipitate . (G) which when filtered leaves a greenish filtrate (H). Identify the compounds A to H.

Explanation

`underset((A))(FeSO_(4))+BaCl_(2)rarr underset("white (B))(BaSO_(4)darr)+FeCl_(2)`
white precipitate of (B) is insoluble in dil. HCl hence in compound (A) `SO_(4)^(-2)` ion is present.
`(A) FeSO_(4).7H_(2)OrarrFeSO_(4)+7H_(2)O`
`2FeSO_(4)underset("Red brown")underset((E))(Fe_(2)O_(3))+underset((C ))(SO_(2)uarr)+underset((D))(SO_(3)uarr)`
`Fe_(2)O_(3)+6HClrarr underset("yellow solution")(2FeCl_(3))+3H_(2)O`
`2FeCl_(3)+H_(2)S rarr 2 FeCl_(2)+2HCl+Sdarr`