Identify the correct statement from the following:

Options

A. Wrought iron is impure iron with 4% carbon
B. Blister copper has blistered appearance due to evolution of `CO_2`
C. Vapour phase refining is carried out for Nickel by Van Arkel method
D. Pig iron can be moulded into a variety of shapes.

Answer

To solve the question, we need to evaluate each of the provided statements to identify which one is correct.

### Step-by-Step Solution:

1. **Evaluate the First Statement:**
- The first statement claims that "wrought iron is an impure iron and has a carbon content of 4%."
- Wrought iron is actually known to be one of the purest forms of iron, with a carbon content of less than 0.08%.
- Therefore, this statement is **incorrect**.

**Hint:** Remember that wrought iron is characterized by its low carbon content, making it a pure form of iron.

2. **Evaluate the Second Statement:**
- The second statement states that "the blistered appearance of copper is due to the evolution of CO2."
- The blistered appearance of copper is actually due to the evolution of SO2 gas when copper is extracted from its sulfide ores (like Cu2S).
- Thus, this statement is also **incorrect**.

**Hint:** Focus on the type of gas released during the extraction of copper from its sulfide ores.

3. **Evaluate the Third Statement:**
- The third statement claims that "vapor phase refining is a method by which we can extract nickel by the van Arkel method."
- However, nickel is extracted through vapor phase refining using the Mond process, not the van Arkel method.
- Therefore, this statement is **incorrect**.

**Hint:** Differentiate between the Mond process and the van Arkel method for extracting nickel.

4. **Evaluate the Fourth Statement:**
- The fourth statement says that "pig iron can be molded in a variety of shapes."
- Pig iron has a high carbon content (3.5% to 4.5%) and can indeed be remelted and molded into various shapes, such as cast iron and steel.
- This statement is **correct**.

**Hint:** Consider the properties of pig iron and its applications in metalworking.

### Conclusion:
The correct statement is the fourth one: "pig iron can be molded in a variety of shapes."