Answer: Sulphur cross-links between chains.
- A Ester linkages between chains
- B Hydrogen bonds within a chain
- C Amide linkages across chains
- D Sulphur cross-links between chains
Correct answer: D. Sulphur cross-links between chains
Explanation: Heating rubber with sulphur forms sulphur cross-links (bridges) between the polyisoprene chains, making the rubber harder, stronger and more elastic.
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.