(i) Sodium is a highly reactive metal. It can catch fire if kept in open. Hence to protect it and prevent accidental fire, it is stored under kerosene oil.
(ii) Due to high reactivity of aluminium, a thin layer of aluminium oxide is formed on it. This protective layer of aluminium oxide prevents the metal from further corrosion. Hence, aluminium can be used for making utensils. This process is anodising.
