Correct Answer - a
(A) is `FeSO_(4).7H_(2)O`
`FeSO_(4)+BaCl_(2)tounderset((B))(BaSO_(4)darr)+FeCl_(2)`
`2FeSO_(4)overset(Delta)tounderset((E))(Fe_(2)O_(3))+underset((C))(SO_(2))+underset((D))(SO_(3))`
`Fe_(2)O_(3)+6HCl tounderset((F))(2FeCl_(3))+3H_(2)O`
`2FeCl_(3)+H_(2)Stounderset((H))(2FeCl_(2))+2HCl+underset((G))(S)`
`2FeCl_(3)+SnCl_(2)to 2FeCl_(2)+SnCl_(4)`
`4FeCl_(3)+3K_(4)Fe(CN)_(6)tounderset("Prussian blue")(Fe_(4)[Fe(CN)_(6)]_(3))+12KCl`