I. During Hall's process, silica is removed as Si (vapour)
II. Bauxite are contaminated with $Fe_2O_3$ is purified in Baeyer's process.
III. During Serpeck's process, AIN is formed.
The correct answer is :
(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
