alleryA polymer that softens on heating and hardens on cooling reversibly is called:
AThermosetting
BConducting polymer
CElastomer
DThermoplastic (e.g., polyethylene, PVC; can be remoulded)
Answer & Solution
Correct answer: D. Thermoplastic (e.g., polyethylene, PVC; can be remoulded)
**Thermoplastics:** linear or branched chains held by weak van der Waals / H-bonds; soften reversibly.
**Thermosets:** cross-linked 3D network
cannot remould after setting.
Most engineering plastics are thermoplastic (recyclable).
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