In the extraction of aluminium
Process `X:` employed for red bauxite to remove iron oxide (main impurity)
Process `Y:` (Serpeck's process): used for while bauxite to remove `Z` (main impurity) then,
Select correct option for the process `X` and impurity `Z`.

Options

A. `X =` Hall and Heroult's process and `Z = SiO_(2)`
B. `X=`Bayer's process and `Z=SiO_(2)`
C. `X=`Serpeck's process and `Y=` iron oxide
D. `X=`Bayer's process and `Y=`iron oxide

Answer

B

Explanation

`(X)`Red bauxite contains the impurities of oxides of iron and silicates. In Bayer process, alumina is dissolved by reacting sodium hydroxide solution leaving behing the insoluble oxide of iron.
`(Y)` White bauxite contains the impurity of silica which is removed by Serpeck's method
`A1_(2) +N_(2) +3C overset(1800^(@)C)rarr 1A1N+ 3CO`,
`SiO_(2) +2Coverset(1800^(@)C)rarrSi +2CO`
`A1N +3H_(2)O rarr A1(OH)_(3) +NH_(3)`,
`2A1(OH)_(3)overset(Delta)rarrA1_(2)O_(3)+3H_(2)O`.