Q6 / 60 · JEE Advanced 2009 (Paper 1) · Chemistry

The correct acidity order of the following is Figure

  • Correct answer
    A
    III $>$ IV $>$ II $>$ I
  • B
    IV $>$ III $>$ I $>$ II
  • C
    III $>$ II $>$ I $>$ IV
  • D
    II $>$ III $>$ IV $>$ I

Solution

A carboxylic acid is stronger acid than phenol, hence both III and IV are stronger acids than both I and II. Also IV has a methyl group that gives electron donating inductive effect and decreases the acid strength. Therefore, III is stronger acid that IV. Between I and II, the dominant electron withdrawing inductive effect of chlorine increases acid strength of phenol slightly, hence II is stronger acid than I. Thus, the overall order is : (a) III $>$ IV $>$ II $>$ I

Hence, the correct answer is option: 'A'.

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