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JEE Main levelOne or more correct optionsDifficulty 2 of 3co198

Use pKa values: 2-chlorobutanoic acid 2.84, 3-chlorobutanoic acid 4.06, 4-chlorobutanoic acid 4.52, o-nitrobenzoic acid 2.17, p-nitrobenzoic acid 3.44, m-nitrobenzoic acid 3.45. Select the correct statements.

  1. A2-chlorobutanoic acid is stronger than 3-chlorobutanoic acid
  2. B4-chlorobutanoic acid is the weakest of the three chlorobutanoic acids
  3. Co-nitrobenzoic acid is stronger than p-nitrobenzoic acid
  4. Dm-nitrobenzoic acid is stronger than p-nitrobenzoic acid by more than one pKa unit

Answer: A, B, C

The acidifying effect of Cl falls as it moves away from (2.84 < 4.06 < 4.52), and the ortho nitro isomer (2.17) is stronger than para (3.44). The meta and para nitro acids differ by only 0.01 units, so the claim of a difference above one pKa unit is wrong.
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