Question

Carbon-based reduction method is not used for the extraction of:

• A. tin from $Sn{O}_2$
• B. iron from $F{e}_2{O}_3$
• C. aluminium from $A{l}_2{O}_3$
• D. magnesium from $CaC{O}_3.MgC{O}_3$

Answer 1

Answer: (C), (D)

The correct options are
C aluminium from $A{l}_2{O}_3$
D magnesium from $CaC{O}_3.MgC{O}_3$

Look for reactive metals. Another clue would be to keep your eyes peeled for compounds
that do not melt easily. Alternatively, think in terms of Ellingham diagram - as in oxides
that would be extremely hard to reduce with carbon.

aluminium is extracted by the Hall-Heroult process where $A{l}_2{O}_3$ is mixed with fluorspar
and cryolite and then subjected to fused electrolysis (non-aqueous).

Likewise, Mg is obtained from fused salt electrolysis of $MgC{l}_2$