In the extraction of aluminium by Hall-Heroult process, purified $$A{l_2}{O_3}$$ is mixed with $$Ca{F_2}$$ to
(i) lower the melting point of $$A{l_2}{O_3}$$
(ii) increase the conductivity of molten mixture.
(iii) reduce $$A{l^{3 + }}$$ into $$Al\left( s \right).$$
(iv) acts as catalyst.
A.
(i) and (ii)
B.
(i), (ii) and (iii)
C.
(iii) and (iv)
D.
(ii), (iii) and (iv)
Answer :
(i) and (ii)
Solution :
In the extraction of aluminium by Hall- Heroult process purified $$A{l_2}{O_3}$$ is mixed with $$Ca{F_2}$$ to lower the melting point by $$A{l_2}{O_3}$$ and increase the conductivity of molten mixture.
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