Which of the following statement(s) is (are) incorrect ?
(A) In Serpeck’s process silica is removed by heating the bauxite to 1800°C with coke in a current of N2
(B) In extraction of lead from galena roasting and self reduction takes place in the same furnance but under different conditions of tempt and supply of air
(C) The tin is obtained by the carbon reduction of black tin.
(D) None
