Question

Assertion (A) : Phenol is more acidic than 4-methylphenol. Reason (R) : The presence of an electron releasing group in phenol makes it more acidic.

• A. Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
• B. Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
• C. Assertion (A) is true, but Reason (R) is false.
• D. Assertion (A) is false, but Reason (R) is true.

Hint:

Electron withdrawing groups increase acidity of phenols, while electron donating groups such as CH$_3$, OCH$_3$ and NH$_2$ decrease acidity.

Answer 1

The Correct Option is C

Step 1: Basis of phenol acidity.
Acidity depends on stability of the phenoxide ion ($\text{C}_6\text{H}_5\text{O}^-$) formed after losing $\text{H}^+$. Electron-withdrawing groups stabilise it (increase acidity); electron-donating groups destabilise it (decrease acidity).
Step 2: Verify the Assertion.
The methyl group in 4-methylphenol is electron-donating (+I effect). It pushes extra electron density onto the already-negative p-methylphenoxide, destabilising it. Plain phenoxide is more stable, so phenol is MORE acidic than 4-methylphenol. Assertion is TRUE.
Step 3: Verify the Reason.
The Reason states that an electron-releasing group makes phenol more acidic. This is the opposite of fact: electron-releasing groups DECREASE acidity by destabilising the conjugate base. Reason is FALSE. \[ \boxed{\text{Option (C): Assertion true, Reason false}} \]