In the vulcanisation of rubber:

Options

A. Sulpher reacts to form a new compound.
B. Sulpher cross-linked are introduced
C. Sulpher forms a very thin protective layer over rubber.
D. All the statements are correct.

Answer

**Step-by-Step Solution:**

1. **Understanding Vulcanization**: Vulcanization is a chemical process that involves heating rubber with sulfur and other additives to improve its properties. This process enhances the strength, elasticity, and durability of rubber.

2. **Analyzing the Options**:
- **Option 1**: "Sulfur reacts to form a new compound." This statement is incorrect because sulfur does not form a new compound during vulcanization; rather, it creates cross-links between rubber molecules.
- **Option 2**: "Sulfur cross-links are introduced." This statement is correct. During vulcanization, sulfur atoms form bridges (cross-links) between the long chains of rubber, which enhances its mechanical properties.
- **Option 3**: "Sulfur forms a very thin protective layer over rubber." This statement is also incorrect. Sulfur does not form a protective layer; it facilitates the formation of cross-links within the rubber structure.
- **Option 4**: "All the statements are correct." This is incorrect since we have identified that some statements are false.

3. **Conclusion**: Based on the analysis, the correct answer is **Option 2: Sulfur cross-links are introduced**.