(a) (i) Zone refining of metals : It is based upon the principle that the impurities are more suluble in the molten state than in ht esolid state of metal.
(ii) Electroltic refining : It is based upon the principle that when electric current is passed, metal ions from the electrolyte are feposited at the cathode in the from of pure metal while an equivalent amount of metal dissolves from anode and goes into eectrolyte solution as metal ions.
`{:("Anode:", M(s) to M_((aq))^(n+)+"ne"^(-)),("Cothode:",M_(aq)^(n+)+"ne"^(-)to M(s)):}`
(b) (i) Metal refined by Mond process is Nickel.
(ii) Metals refined by van Arkel method is Zirconium and Titanium.