Q. Electrolytic reduction of alumina to aluminium by Hall-Heroult process is carried out
A) In the presence of $NaCl$
B) In the presence of fluorite
C) In the presence of cryolite which forms a melt with lower melting point
D) In the presence of cryolite which forms a melt with high melting point
Explanation
(c)
In the extraction of $Al,Al_{2}O_{3}$ is melted with cryolite$\lbrack{Na}_{3}(AlF_{6})\rbrack$. Cryolite improves the electrical conductivity of the alumina and lowers the m.p. of the mixture to about $950℃$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.