What is the Colour of Ferrous Sulphate Crystals How Does this Colour Change After Heating

Answer: The colour that ferrous sulphate crystals (FeSO₄.7H₂O) exhibit is light green. 

On heating, the water in the crystals evaporates, resulting in the formation of anhydrous ferrous sulphate (FeSO₄), which changes the crystals’ colour from light green to white. The chemical reaction is FeSO₄⋅7H₂O(s) heat→ FeSO₄+7H₂O.