Answer: Softened and reshaped on heating.
- A Softened and reshaped on heating
- B Rarely melted in routine practice
- C Mainly used once overall in most cases
- D Cross-linked permanently under typical conditions
Correct answer: A. Softened and reshaped on heating
Explanation: Thermoplastics (like polyethylene, PVC) soften reversibly on heating and can be remoulded.
Addition polymerisation simply links monomers containing a double bond with nothing left over, while condensation polymerisation joins two different monomers through a reaction (often forming an ester or amide bond) that releases a small molecule like water at each step.
Concept context
Large molecules made of repeating monomer units. Covers addition and condensation polymerisation, natural and synthetic polymers (nylon, PVC, Bakelite, natural rubber), and their real-world industrial applications.