Which of the following statements is incorrect ?

Options

A. In Hall`-` Heroult process, the electrolyte used is a molten mixture of alumina, sodium hydroxide and cryolite
B. Lead is extracted from its chief ore by both carbon reduction and self reduction.
C. Zinc is extracted from its chief ore by carbon reduction.
D. Extraction of gold involves the leaching of ore with cyanide solution followed by reduction with zinc.

Answer

1

Explanation

`(1)` It is molten mixture of alumina and cryolite
`(2) 2PbS+3O_(2)rarr2PbO+2SO_(2)`
`PbS+2PbOrarr3Pb+SO_(2)("self reduction")`
`PbO+CrarrPb+CO("carbon reduction")`
`(3)ZnO+CrarrZn+CO("carbon reduction")`.
`(4) 4Au(s)+8CN^(-)(aq)+2H_(2)O(aq)+O_(2)(g)rarr4[Au(CN)_(2)]^(-)(aq)+4OH^(-)(aq)-`leaching
`2[Au(CN)_(2)]^(-)(aq)+Zn(s)rarr2Au(s)+[Zn(CN)_(4)]^(2-)(aq)-`reduction