Gold (Ag) and copper (Cu) obtained after extraction are in impure form. So, metals like gold and copper are refined by electrolytic refining. Other than gold and copper, electrolytic refining is used for metals such as Zn and Ag. Sodium ...

(i) it is does not react with water (ii) it reacts violently with water (iii) it reacts less violently with water (iv) bubbles of hydrogen gas formed stick to the surface of calcium