In vulcanized rubber.................are in form of cross links.

Answer

**Step-by-Step Solution:**

1. **Understanding Vulcanized Rubber**: Vulcanized rubber is produced by treating natural rubber with sulfur. This process enhances the properties of rubber, making it more durable and elastic.

2. **The Process of Vulcanization**: The vulcanization process involves heating rubber with sulfur at temperatures ranging from 373 K to 415 K. This heating allows sulfur to react with the rubber.

3. **Formation of Cross-links**: During vulcanization, sulfur atoms create cross-links between the long chains of rubber molecules. These cross-links occur at the reactive sites of the double bonds present in the rubber's structure.

4. **Effect of Cross-linking**: The formation of these cross-links leads to an increase in the tensile strength and elasticity of the rubber. It transforms the rubber from a soft and flexible material to a more rigid and durable form.

5. **Identifying the Cross-links**: In the context of the question, the cross-links formed in vulcanized rubber are specifically sulfur atoms. These sulfur atoms connect different rubber polymer chains, resulting in a network structure.

6. **Final Answer**: Therefore, in vulcanized rubber, **sulfur atoms** are in the form of cross-links.

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