Match items of Column I with the items of Column II and assign the correct code :

Column $${\rm I}$$			Column $${\rm I}$$$${\rm I}$$
(A)	Cyanide process		(i)	Ultrapure Ge
(B)	Froth floatation process		(ii)	Dressing of ZnS
(C)	Electrolytic reduction		(iii)	Extraction of Al
(D)	Zone refining		(iv)	Extraction of Au
			(v)	Purification of Ni

In the extraction of copper from its sulphide ore. the metal is finally obtained by the reduction of cuprous oxide with

''Metals are usually not found as nitrates in their ores.'' Out of the following two (I and II) reasons which is/are true for the above observation?
I.  Metal nitrates are highly unstable.
II.  Metal nitrates are highly soluble in water.

The metal oxide which cannot be reduced to metal by carbon is