Question

Given below are two statements: one is labeled as Assertion (A) and the other is labeled as Reason (R).
Assertion (A): Acidic nature follows the order:

Reason (R): F is a better electron-withdrawing group than Cl
In the light of the above statements, write the detailed answer:

• (A) and (R) both are correct and (R) is the correct explanation of (A)
• (A) and (R) both are correct, but (R) is not the correct explanation of (A)
• (A) is correct but (R) is not correct
• (A) is incorrect but (R) is correct

Answer 1

The Correct Option is B

To solve this question, we need to analyze the given assertion and reason related to the acidic nature of substituted phenols.

Assertion (A): Acidic nature follows the order: 

Reason (R): F is a better electron-withdrawing group than Cl.

We need to evaluate whether both (A) and (R) are correct, and if (R) is the correct explanation for (A).

1. The acidic nature of phenols is influenced by the substituents present on the benzene ring.

• Electron-withdrawing groups increase acidity as they stabilize the negative charge on the phenoxide ion.

2. In the given structures:

• Compound with Cl substituent (leftmost): Chlorine is an electron-withdrawing group due to its electronegativity and ability to delocalize electron density through resonance.
• Compound with F substituent (middle): Fluorine is even more electronegative than chlorine, making it a strong electron-withdrawing group by induction.
• Compound with CH₃ substituent (rightmost): Methyl group is an electron-donating group, reducing acidity.

3. Comparison of acidity:

• The fluorine-substituted phenol is more acidic than the chlorine-substituted phenol because fluorine is a stronger electron-withdrawing group than chlorine.
• The methyl-substituted phenol is the least acidic due to the electron-donating effect of the methyl group.

4. Therefore, the order of acidity is: F > Cl > CH₃

Conclusion:

• (A) is correct because it reflects the proper order of acidity based on the electron-withdrawing or electron-donating nature of the substituents.
• (R) is also correct that F is a better electron-withdrawing group than Cl.
• However, while (R) is true, it does not solely explain the order in (A) because the full explanation involves comparing all substituents' effects.

Therefore, the correct answer is: (A) and (R) both are correct, but (R) is not the correct explanation of (A).