Which of the following is an elastomer?

Options

A. Vulcanized rubber
B. Dacron
C. Polystyrene
D. Melamine

Answer

To determine which of the following options is an elastomer, we need to understand the definition and characteristics of elastomers.

### Step-by-Step Solution:

1. **Understanding Elastomers**:
- Elastomers are materials that exhibit rubber-like properties. They can stretch significantly and return to their original shape when the stress is removed. This elasticity is due to the weak intermolecular forces present in the polymer chains.

2. **Identifying Examples of Elastomers**:
- Common examples of elastomers include natural rubber and synthetic rubbers like Buna-N and Buna-S. These materials have the ability to undergo deformation and return to their original shape.

3. **Analyzing the Given Options**:
- **Option 1: Vulcanized Rubber**: This is a type of rubber that has been treated with sulfur to improve its properties, including elasticity. It is indeed an elastomer.
- **Option 2: Dacron**: This is a polyester made from ethylene glycol and terephthalic acid. It is not an elastomer but a type of thermoplastic.
- **Option 3: Polystyrene**: This is a polymer made from styrene and is not elastic; it is a rigid thermoplastic.
- **Option 4: Melamine**: This is a thermosetting plastic made from melamine and formaldehyde. It does not have elastic properties and is not an elastomer.

4. **Conclusion**:
- The only option that qualifies as an elastomer is **Vulcanized Rubber**.

### Final Answer:
**Vulcanized Rubber** is an elastomer.