Question

Observe the following statements regarding purification of bauxite:
I. During Hall's process, silica is removed as Si (vapour).
II. Bauxite ore contaminated with $F{e}_2{O}_3$ is purified in Baeyer's process.
III. During Serpeck's process, $AlN$ is formed.

• A. I , II and III are correct
• B. Only I and II are correct
• C. Only I and III are correct
• D. Only II and III are correct

Answer 1

Answer: (D)

Only II and III are correct

• Hall-Heroult's process is the electrolysis refining of bauxite ore. $C{O}_2$ is removed as impurities. Thus statement $I$ is incorrect.
• The Bayer process is the principal industrial means of refining bauxite to produce alumina (aluminium oxide).

$Ti{O}_2,F{e}_2{O}_3,Si{O}_2$ exists as impurities in the bauxite ore. All the impurities are removed during this purification process.

Thus statement $II$ is correct.

• Serpeck's Process:

$A{l}_2{O}_3.2H_{2}O+3C+N_2\to 2AlN+3CO+2H_{2}O$

$AlN$ is formed in the Serpeck's process. Hence III is correct statement.

Option D is correct.