Which of the following statements is true about PVC (polyvinyl chloride) and polythene?

Options

A. They are thermoplastic.
B. They are thermosetting plastics.
C. They are examples of natural substances.
D. They are natural fibres.

Answer

To determine which statement is true about PVC (polyvinyl chloride) and polythene, we need to analyze their characteristics and classifications.

### Step-by-Step Solution:

1. **Identify the Type of Plastics**:
- PVC and polythene are both types of plastics. We need to classify them as either thermoplastics or thermosetting plastics.

2. **Understand Thermoplastics**:
- Thermoplastics are materials that can be re-heated and re-molded. This means that once they are shaped, they can be melted and reshaped multiple times without undergoing any significant chemical change.

3. **Understand Thermosetting Plastics**:
- In contrast, thermosetting plastics cannot be re-molded or re-heated once they have been set into a shape. They undergo a chemical change when they are formed, making them rigid and unable to be reshaped.

4. **Classify PVC and Polythene**:
- Both PVC and polythene fall under the category of thermoplastics. This means they can be re-heated and re-molded.

5. **Conclusion**:
- Therefore, the true statement regarding PVC and polythene is that they are thermoplastics. They are not thermosetting plastics, nor are they natural substances or fibers.

### Final Answer:
PVC and polythene are both thermoplastics.

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