During Serpeck's process, silica is eliminated as

Observe of the following statements regarding purification of bauxite: (I) During Hall's process, silica is removed as Si(vapour) Bauxite ore contaminated with Fe_(2)O_(3) is purfied in Baeyer's process. During Serpeck's process, AIN is foremed The correct answer is:

Observe the following statements regarding purification of bauxite. I. During Hall's producess, silica is removed as Si (vapour). II. Bauxite ore contaminated with Fe_(2)O_(3) is purified by Baeyer's process. III. During Serpeck's process. AlN is formed. The correct answer is

Which one of the following is used to remove silicon dioxide in Serpeck's process of purification of bauxite?