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

	Column I		Column II
a)	Cyanide process	(i)	Ultrapure Ge
b)	Froth flotatiion process	(ii)	Dressing of ZnS
c)	Electrolytic reduction	(iii)	Extraction of Al
d)	Zone refining	(iv)	Extraction of Au
		(v)	Purification of Ni

a	b	c	d
iv	ii	iii	i
i	ii	iii	iv
iv	iii	ii	i
iii	ii	i	iv

Cyanide process– Extraction of gold and silver.
Froth floatation – Concentration of sulphide ores.
Electrolytic reduction – Extraction of highly electropositive metals like Na, K, Mg, Ca, Al, etc.
Zone refining – Producing semiconductors and other metals of very high purity.
So the correct option is- 
a – iv, b – ii, c – iii, d – i