Why should foodstuffs with acid component not be stored in metallic containers?

23 Aluminium metal is nowadays widely used for making household utensil and electric wires. What is your inference of aluminium as a metal? 24 Some non-metals like phosphorus are kept in water to protect them from atmospheric oxygen. State the property of the non-metals utilized here. 26 A substance was burnt in air. The white residue obtained was added to water. This water solution turned red litmus into blue. State whether the substance is a metal or a non-metal? 27 An oxide solution of which of the following elements will turn blue litmus red? Calcium sulphur iron sodium.