COMEDK202510 May 2025Evening ShiftChemistryGeneral Organic ChemistryActual
Two statements, One Assertion and the other Reason, are given. Which one of the following is the correct option? Assertion: The acid strength of 4 compounds in the descending order is p-Nitrophenol > p-Methoxyphenol > Phenol > p- chlorophenol. Reason: Electron withdrawing groups increase the acid strength while Electron donating groups decrease the acid strength of Phenol and its derivatives.
Options
- ABoth Assertion and Reason are correct.
- BAssertion is correct but Reason is wrong.
- CAssertion is wrong but Reason is correct.
- DBoth Assertion and Reason are wrong.
Correct answer
C. Assertion is wrong but Reason is correct.
Step-by-step solution
The acid strength of substituted phenols depends on the electronic effects of the substituents. Electron withdrawing groups (EWG) stabilize the phenoxide ion through inductive (-I) and resonance (-M) effects, thereby increasing acidity. Electron donating groups (EDG) destabilize the phenoxide ion through inductive (+I) and resonance (+M) effects, thereby decreasing acidity. Comparing the substituents: 1. p-Nitrophenol: -NO₂ is a strong EWG ( -I and -M effects), making it the most acidic. 2. p-Chlorophenol: -Cl is a