Question

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 N2A
• 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 1

Answer: (D)

None

Answer 2

(1) White bauxite contains the impurity of silica which is removed by heating with coke in a stream of N2

SiO2 + 2C $\overset{\quad 1800^{0}C\quad}{\rightarrow}$ Si+ 2CO ; Al2O3 + 3C + N2 $\overset{\quad 1800^{0}C\quad}{\rightarrow}$ 2AlN + 3CO

(2) 2PbS + 3O2 $\underset{air}{\overset{\quad lowertemperature\quad}{\rightarrow}}$ 2PbO + SO2 ; 2PbO + PbS $\overset{\quad highertemperature\quad}{\rightarrow}$ 3Pb + SO2

(3) SnO2 (black tin contains 60–70% SnO2) + 2C $\overset{\quad\Delta\quad}{\rightarrow}$ Sn + 2CO.