Anhydrous copper sulphate turns ____________ on the addition of few drops of water.

• Salts that do not contain any water along with the salts are anhydrous substances.
• Salts that contain water molecules along with salts like Copper sulphate pentahydrate $({\mathrm{CuSO}}_4.5{\mathrm{H}}_2\mathrm{O})$ are hydrated substances.
• These water molecules give the crystals their shape and color.
• When hydrated copper sulphate is exposed to dry air, it changes its color from blue to white.

Anhydrous copper sulphate turns blue with the addition of a few drops of water.