Match List - I with List - II :

	List - I		List - II
(a)	Mercury	(i)	Vapour phase refining
(b)	Copper	(ii)	Distillation refining
(c)	Silicon	(iii)	Electrolytic refining
(d)	Nickel	(iv)	Zone refining

Choose the most appropriate answer from the option given below :

The chemical that is added to reduce the melting point of the reaction mixture during the extraction of aluminium is :

Match List - I with List - II :

	List - I		List - II
(a)	Haematite	(i)	$$A{l_2}{O_3}\,.\,x{H_2}O$$
(b)	Bauxite	(ii)	$$F{e_2}{O_3}$$
(c)	Magnetite	(iii)	$$CuC{O_3}\,.\,Cu{(OH)_2}$$
(d)	Malachite	(iv)	$$F{e_3}{O_4}$$

Choose the correct answer from the options given below :

The point of intersection and sudden increase in the slope, in the diagram given below, respectively, indicates :