JEE Advanced levelOne or more correct optionsDifficulty 3 of 3mt046
Select the correct statement(s) about the processes used to obtain pure alumina from bauxite.
AIn Serpeck's process AlN is formed by heating bauxite with coke in a stream of nitrogen
BIn Hall's process fusion of the ore with NaX2COX3 gives NaAlOX2 with the evolution of COX2
CIn Baeyer's process the iron(III) oxide of the ore dissolves in hot concentrated NaOH as a ferrate and is later precipitated
DBaeyer's process is best suited to bauxite of low silica content
Answer: A, B, D
Silica consumes alkali in Baeyer's process, so low-silica bauxite is preferred (true). FeX2OX3 is basic and does not dissolve in alkali; it stays as red mud (statement 2 false). Hall's process: AlX2OX3+NaX2COX32NaAlOX2+COX2 (true). Serpeck's process: AlX2OX3+3C+NX22AlN+3CO (true).