JEE Main levelSingle correct optionDifficulty 2 of 3pl212
During vulcanisation, sulfur cross-links form chiefly at
Athe terminal ester groups of the chain
Bthe backbone C−C single bonds, which are cleaved
Cthe methyl groups, by breaking C−H bonds of the saturated carbons only
Dthe allylic methylene positions next to the C=C bonds of the polyisoprene chain
Answer: D
In NCERT-level treatment the reactive sites are the double bonds and the allylic hydrogens adjacent to them. Sulfur bonds there and bridges neighbouring chains by −S− or −S−SX− links. Natural rubber has no ester groups.