Rock salt is an ore of one of the following metals. This metal is :

84 During galvanization, iron metal is given a thin coating of one of the following metals. This metal is: 85 Which of the following metals are extracted by the electrolysis of their molten chlorides? 87 The articles made of silver metal become dark on prolonged exposure to air. This is due to the formation of a layer of its : 88 A sulphide ore is converted into metal oxide by the process of :