Which of the following statements about the vulcanisation of natural rubber are correct?

ASulfur bridges join different polyisoprene chains and so restrict slipping of chains.
BThe number of $C = C$ bonds per chain rises because new double bonds form with sulfur.
CA higher sulfur content gives more cross-links and a harder, less stretchable material.
DVulcanised rubber recovers its shape after stretching better than raw rubber.

Answer: A, C, D

Cross-links stop chains sliding past each other, so elastic recovery improves, and more sulfur gives more cross-links and a harder product. Sulfur attaches at double bonds or allylic sites, so unsaturation decreases and option 1 is false.

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