Green colour of Ferrous sulphate changes to which of the following colour upon heating?

White

The correct answer is option 2. White.

The green color of ferrous sulfate (\(FeSO_4\)) changes to white upon heating. When ferrous sulfate is heated, it undergoes dehydration, losing its water molecules and forming anhydrous ferrous sulfate (\(FeSO_4\cdot nH_2O\)). This anhydrous form of ferrous sulfate is white in color. The loss of water molecules changes the appearance of the compound from green (hydrated form) to white (anhydrous form).

So, the correct answer is White.