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JEE Main levelSingle correct optionDifficulty 2 of 3o2083

HCl does not show the peroxide effect with alkenes mainly because

  1. AHCl is a weaker acid than HBr
  2. Bthe C-Cl bond formed is weaker than the C-Br bond
  3. Cabstraction of hydrogen from H-Cl by the carbon radical is endothermic
  4. D cannot be formed from peroxide

Answer: C

The H-Cl bond (about 431 kJ/mol) is stronger than the C-H bond formed, so the step is endothermic and the chain does not propagate. HBr has a weaker H-Br bond, so the same step is exothermic.
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