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JEE Advanced levelSingle correct optionDifficulty 3 of 3nc128

Assertion: 3-Nitroaniline is a stronger base than 4-nitroaniline. Reason: In 4-nitroaniline the nitrogen lone pair is delocalised onto the nitro group through the -R effect, whereas from the meta position only the -I effect of the nitro group operates.

  1. ABoth Assertion and Reason are true and the Reason is the correct explanation of the Assertion
  2. BBoth Assertion and Reason are true but the Reason is not the correct explanation of the Assertion
  3. CAssertion is true but Reason is false
  4. DAssertion is false but Reason is true

Answer: A

From the para position the nitro group withdraws electrons by both -I and -R effects, with the amino lone pair delocalised into the nitro group, which lowers basicity strongly (conjugate acid pKa about 1.0). From the meta position resonance cannot place charge on the carbon bearing the amino group, so only -I acts (pKa about 2.5). The Reason correctly explains the Assertion.
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