When ethene is heated at 350-370 K under a pressure of `1000-2000` atm in presence of trace of oxygen or peroxide .............is obtained.

Answer

To solve the question, we need to understand the process described:

1. **Identify the Reactant**: The question mentions ethene, which is represented by the chemical formula \( \text{C}_2\text{H}_4 \).

2. **Conditions of the Reaction**: The reaction takes place under specific conditions:
- Temperature: 350-370 K
- Pressure: 1000-2000 atm
- Presence of a trace of oxygen or peroxide

3. **Understanding the Reaction**: Under these conditions, ethene undergoes a polymerization reaction. This means that multiple ethene molecules will join together to form a larger molecule, which is a polymer.

4. **Product Formation**: The polymer formed from ethene is known as polyethylene. There are two main types of polyethylene:
- High-Density Polyethylene (HDPE)
- Low-Density Polyethylene (LDPE)

5. **Conclusion**: Therefore, when ethene is heated at the specified conditions in the presence of oxygen or peroxide, polyethylene is obtained.

### Final Answer:
When ethene is heated at 350-370 K under a pressure of 1000-2000 atm in the presence of a trace of oxygen or peroxide, **polyethylene** is obtained.