Which of the following statement(s) is (are) incorrect ?

Options

A. In serpeck's process silica is removed by heating the bauxite to `1800^@C` with coke in a current of `N_2`
B. In extraction of lead from galena roasting and self reduction takes place in the same furnace but under different conditions of temperature and supply of air
C. The tin is obtained by the carbon reduction of black tin
D. None

Answer

D

Explanation

White bauxite contains the impurity of silica which is removed by heating with coke in a stream of N.
`SiO_2 + 2C overset(1800^@C)to Siuarr+2CO,Al_2O_3+3C+N_2overset(1800^@)to2AIN+3CO`
(B)`2PbS+3O_2underset(air)overset(temperature)to2PbO+SO_2,2PbO+PbSoverset(higher temperature)to3Pb+SO_2`
( C)`SnO_2` (black tin contains 60-70% `SnO_2`)+2C`overset(Delta)toSn+2CO`