Give reasons :-
(1) Roasting is carried out on sulphide ores and not on carbonate ores.
(2) Lead is used for welding purposes but its alloy solder is used.
(3) Zine is used as a cathode in dry cells and is also alloyed with copper in the manufacture of brass.
(4) Hydrogen gas is liberated on addition of aluminium to dilute sulphuric acid.
(5) Extraction of aluminium from its ore is based on its position in the activity series.