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JEE Advanced levelOne or more correct optionsDifficulty 3 of 3pl087

Neoprene is made by 1,4-addition polymerisation of 2-chlorobuta-1,3-diene, giving the repeat unit (, C 12, H 1, Cl 35.5). Which statements are correct?

  1. AEach repeat unit contains one bond.
  2. BThe double bond in the polymer lies between the carbons that were C-2 and C-3 of the monomer, and C-2 carries chlorine.
  3. CThe polymer is formed only by 1,2-addition, so chlorine ends up in a side chain on a saturated carbon.
  4. DThe repeat unit has a molar mass of 88.5 g/mol.

Answer: A, B, D

1,4-addition shifts the double bond to C-2=C-3, keeping Cl on C-2, and the unit mass is . Exclusive 1,2-addition is not what gives neoprene, so option 2 is false.
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