Which one of the following statements is incorrect ?

Options

A. In Hall-Heroult process, the electrolytes used is a molten mixture of alumina, sodium hydroxide and cryolite.
B. Lead is extracted form 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 cyanides solution followed by reduction with zinc.

Explanation

To determine which statement is incorrect, we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Statement A**: "In the whole hydrolysis process, the electrolytes used is a molten mixture of alumina, sodium hydroxide, and cryolite."
- **Analysis**: The electrolytes used in the Hall-Héroult process for the production of aluminum are typically a molten mixture of alumina (Al₂O₃), cryolite (Na₃AlF₆), and sometimes fluorspar (CaF₂). Sodium hydroxide is not used as an electrolyte in this process.
- **Conclusion**: This statement is incorrect.

2. **Statement B**: "Lead is extracted from cheap ore by both carbon reduction and self-reduction."
- **Analysis**: Lead can indeed be extracted from its ores using both carbon reduction (for example, PbO + C → Pb + CO₂) and self-reduction (for example, PbO + PbS → Pb + SO₂). This statement is correct.
- **Conclusion**: This statement is correct.

3. **Statement C**: "Zinc is extracted from its chief ore by carbon reduction."
- **Analysis**: Zinc is primarily extracted from zinc blende (ZnS). The process involves roasting to form zinc oxide (ZnO), which is then reduced using carbon (ZnO + C → Zn + CO₂). This statement is correct.
- **Conclusion**: This statement is correct.

4. **Statement D**: "Extraction of gold involves the leaching of ore with cyanide solution followed by the reduction with zinc."
- **Analysis**: The extraction of gold typically involves cyanidation, where the gold ore is treated with a cyanide solution to form a soluble complex. This complex is then reduced using zinc to precipitate gold. This statement is correct.
- **Conclusion**: This statement is correct.

### Final Answer:
The incorrect statement is **A**: "In the whole hydrolysis process, the electrolytes used is a molten mixture of alumina, sodium hydroxide, and cryolite."

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