Cupellation method is used for the purification of which of the following metals?

Which method is not correct given for refining of crude metals?

In the electrolytic purification of copper,some gold is found in the:

What is the process of refining aluminum by the electrolytic refining method called?

In the electrolytic refining of an impure metal,a rod of impure metal is used as the anode and a rod of pure metal is used as the cathode,and the aqueous solution of its salt is electrolyzed. Which of the following metals cannot be refined by this method?

Poling is employed in the refining of: