Question

In the extraction of aluminium from bauxite, cryolite is used to

• A. decrease the boiling point of aluminium
• B. purify the bauxite
• C. make the mass lighter
• D. decrease melting point of alumina and increase conductivity

Answer 1

Answer: (D)

decrease melting point of alumina and increase conductivity

Answer 2

The M.P of alumina is $2000^{\circ} C$, which is reduced to $900^{\circ}C$ in the presence of cryolite ${(Na_3AlF_6)}$ and mixture is also a good conductor of electricity. Thus, cryolite decreases the energy consumption during the process.