Name the following:(i) Two metals which are found in the free or native state.(ii) The mixture of materials fed into a furnace to extract a metal.(iii) The rocky impurities present in an ore.(iv) The substance added to get rid of gangue in the extraction of metal.(v) The process of heating a substance very strongly in such a way that it does not combine with oxygen.(vi) The process in which an ore is heated in air so that oxygen gets added to it to form the oxides.(vii) Ore of iron referred to as "fool's gold".(viii) The most abundant metal in the crust of the earth.(ix) The chief ore of aluminium.(x) The substance added along with alumina in the Hall-Heroult's process.(xi) The materials used as electrodes in the electrolytic extraction of aluminium.(xii) The kind of welding in which aluminium powder is used.(xiii) The chief metal present in magnalium and duralumin.(xiv) Two metals which occur in nature in free state as well as in combined state.(xv) Name two metals which are always found in combined state.