Question

Two statements, One Assertion [A] and the other Reason [R] are given. Identify the correct option.
Assertion [A]: The decreasing order of the acidic character of the following is \(B>D>A>C\).
Reason [R]: Fluorine has larger \(-I\) effect than Cl and Br.

• A. A is correct but R is wrong.
• B. Both A and R are correct and R is the correct explanation of A.
• C. A is wrong but R is correct.
• D. Both A and R are correct but R is not the correct explanation of A.

Hint:

Acidity is influenced not only by inductive effect but also by position of substituent and structural factors. Always consider the overall molecular environment.

Answer 1

The Correct Option is D

Step 1: Understanding acidic strength in substituted cyclohexanols.
The acidic strength of alcohols depends on the stability of the conjugate base (alkoxide ion).
Electron withdrawing groups increase acidity by stabilizing the negative charge on oxygen.
Electron donating groups decrease acidity by destabilizing the alkoxide ion.

Step 2: Effect of halogens.
Halogens such as F, Cl, and Br show \(-I\) (electron withdrawing) effect.
This increases acidity of the alcohol.
Stronger the \(-I\) effect, greater is the acidity.

Step 3: Comparing substituents in the given compounds.
- Compound \(B\): Contains Cl (moderate \(-I\) effect)
- Compound \(D\): Contains F (strong \(-I\) effect)
- Compound \(A\): Contains Br (weaker \(-I\) effect than Cl)
- Compound \(C\): Contains \(CH_3\) group (electron donating, decreases acidity)
Thus, acidity decreases in the order:
\[ B>D>A>C \] So, the assertion is correct.

Step 4: Checking the reason.
The reason states that fluorine has greater \(-I\) effect than Cl and Br.
This statement is correct because electronegativity order is:
\[ F>Cl>Br \] So, \(-I\) effect follows the same order.

Step 5: Evaluating whether reason explains assertion.
Although fluorine has the strongest \(-I\) effect, the given order places compound \(B\) (Cl) above compound \(D\) (F).
Thus, the trend in assertion is not solely explained by \(-I\) effect.
Other factors such as position, molecular structure, and steric effects also influence acidity.

Step 6: Conclusion.
Both Assertion and Reason are correct statements.
However, Reason does not correctly explain the Assertion.

Step 7: Final Answer.
\[ \boxed{\text{Option (D)}} \]