How can a reaction with positive ΔG be made to occur?

Which of the following is not refined by zone refining method?

Roasting results in the formation of oxides. But why are oxide ores are subjected to roasting?

What is the voltage at which electrolysis of brine takes place?

What is the composition of brass?

What is the anode and cathode used in Hall-Heroult process?

What is the process used to recover the metal from its soluble complex obtained after leaching?

What is the criterion of the feasibility of a reaction at any temperature?