Which of the following statement is incorrect?

Options

A. In Hall-Heroult process, the electrolyte used is a molten mixture of alumina, crylite and fluorspar.
B. Pig iron is the purest form of iron .
C. copper is extracted from its ore by self reduction .
D. Zinc is extracted from its ore zinc blende by self reduction .

Explanation

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

### Step 1: Analyze the first statement
**Statement 1:** In Paul Heroult's process, the electrolyte used is a molten mixture of alumina, cryolite, and fluorospar.

- **Explanation:** The Hall-Heroult process is indeed used for the extraction of aluminum. The electrolyte consists of a molten mixture of alumina (Al₂O₃), cryolite (Na₃AlF₆), and fluorospar (CaF₂). The addition of cryolite and fluorospar is essential because alumina is a poor conductor of electricity. Therefore, this statement is **true**.

### Step 2: Analyze the second statement
**Statement 2:** Pig iron is the purest form of iron.

- **Explanation:** Pig iron contains about 2-3% carbon, making it an impure form of iron. The purest form of iron is wrought iron, which contains only about 0.2-0.3% carbon. Therefore, this statement is **false**.

### Step 3: Analyze the third statement
**Statement 3:** Copper is extracted from its ore by self-reduction.

- **Explanation:** Copper is indeed extracted from its ores through a process that involves self-reduction. The reaction involves Cu₂O and Cu₂S, leading to the formation of copper metal and sulfur dioxide. Therefore, this statement is **true**.

### Step 4: Analyze the fourth statement
**Statement 4:** Zinc is extracted from its ore, zinc blende, by self-reduction.

- **Explanation:** Zinc blende (ZnS) is not extracted by self-reduction. The extraction process involves roasting zinc blende to convert it into zinc oxide (ZnO), followed by reduction with carbon (coke) to produce zinc metal. Therefore, this statement is **false**.

### Conclusion
Based on the analysis:
- Statement 1: True
- Statement 2: False (incorrect)
- Statement 3: True
- Statement 4: False (incorrect)

The incorrect statements are **2 and 4**.