Which of the following is thermoplastic ?

Options

A. Dacron
B. Nylon
C. Polythene
D. All of these

Answer

To determine which of the given options is a thermoplastic, we need to understand the characteristics of thermoplastics. Thermoplastics are polymers that can be repeatedly softened by heating and hardened by cooling. They have linear or slightly branched structures, which allows them to be reshaped when heated.

### Step-by-Step Solution:

1. **Understand the Definition of Thermoplastics**:
- Thermoplastics are materials that become soft when heated and hard when cooled. This process is reversible.

2. **Identify the Characteristics of Thermoplastics**:
- They have linear or slightly branched polymer chains.
- They do not have strong cross-linking between chains, which allows them to flow when heated.

3. **Review the Given Options**:
- We need to analyze the options provided to identify which one fits the definition of a thermoplastic.

4. **Analyze Each Option**:
- **Option A: Polystyrene** - This is a thermoplastic known for its rigidity and ability to be molded when heated.
- **Option B: Polyethylene (Polythene)** - This is also a thermoplastic, widely used in various applications due to its flexibility and durability.
- **Option C: PVC (Polyvinyl Chloride)** - This is another thermoplastic, commonly used in construction and plumbing.
- **Option D: Dacron (Polyester)** - This is a type of fiber and is not classified as a thermoplastic because it has a more rigid structure and does not exhibit the same heating and cooling properties.

5. **Conclusion**:
- Based on the analysis, the correct thermoplastic from the options is **Polystyrene, Polyethylene, and PVC**. However, since Dacron is not a thermoplastic, it is the one that does not belong to this category.

### Final Answer:
The thermoplastic from the options given is **Polyethylene (Polythene)**.