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JEE Main levelSingle correct optionDifficulty 2 of 3o2071

Which is the correct order of stability of the following free radicals? (i) (ii) (iii) (iv)

  1. A(iv) (iii) (ii) (i)
  2. B(iv) (ii) (iii) (i)
  3. C(iii) (iv) (ii) (i)
  4. D(i) (ii) (iii) (iv)

Answer: A

Alkyl radicals are stabilised by hyperconjugation with adjacent C-H bonds. The number of such bonds increases from methyl (none) to ethyl (3) to isopropyl (6) to tert-butyl (9), so stability is methyl.
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