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NEET levelSingle correct optionDifficulty 1 of 3g2010

In aqueous solution the pKa values of the conjugate acids are 4.6 for the anilinium ion () and 10.6 for the methylammonium ion (). Which statement is correct?

  1. Athe anilinium ion is the stronger acid, so aniline is a stronger base than methylamine
  2. Bthe methylammonium ion is the stronger acid, so methylamine is a weaker base than aniline
  3. Cthe anilinium ion is the stronger acid, so aniline is a weaker base than methylamine
  4. Dboth ions have the same acidity, so the two amines have equal basicity

Answer: C

A lower pKa means a stronger acid. Anilinium (4.6) is a stronger acid than methylammonium (10.6). The stronger the conjugate acid, the weaker the parent base, so aniline is a weaker base than methylamine.
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