When blue crystals of ferrous sulphate (FeSO₄.7H₂O) are heated, then 7 water molecules are lost & anhydrous ferrous sulphate is formed.

When silver chloride, AgCl is placed in sunlight for some time, then silver chloride changes into grey coloured silver metal & chlorine gas. 2AgCl (s) + Sunlight → 2Ag(s) + Cl₂ (s)