Which of these is not a property of thermoplastics?

Options

A. They are soft
B. They can be stretched easily
C. They are made of cross-linking polymers.
D. They can be remoulded into different shapes.

Explanation

**Step-by-Step Solution:**

1. **Understanding Thermoplastics**: Thermoplastics are a type of plastic that becomes soft when heated and hard when cooled. They are made of linear polymers, which means their molecular structure consists of long, straight chains.

2. **Analyzing the Options**:
- **Option 1**: "They are soft." - This is true for thermoplastics because they can be easily molded when heated.
- **Option 2**: "They can stretch easily." - This is also true as thermoplastics can be deformed when heated.
- **Option 3**: "They are made of cross-linked polymers." - This is false. Thermoplastics are made of linear polymers, not cross-linked polymers. Cross-linked polymers are characteristic of thermosetting plastics, not thermoplastics.
- **Option 4**: "They can remold into different shapes." - This is true because thermoplastics can be reshaped multiple times upon heating.

3. **Identifying the Incorrect Property**: From the analysis, option 3 is the only statement that is not a property of thermoplastics.

4. **Conclusion**: Therefore, the answer to the question "Which of these is not a property of thermoplastics?" is **Option 3: They are made of cross-linked polymers**.

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