Assertion : Phenol and benzoic acid can be distinguished by `Na_(2)CO_(3).`
Reason : Benzoic acid is stronger acid than phenol, hence reacts with `Na_(2)CO_(3)`.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Answer

To solve the given assertion and reason question, we will analyze both statements step by step.

### Step 1: Understand the Assertion
The assertion states that phenol and benzoic acid can be distinguished by sodium carbonate (Na₂CO₃).

### Step 2: Analyze the Reactivity with Sodium Carbonate
Sodium carbonate is a weak base. It reacts with stronger acids to produce carbon dioxide gas (CO₂) and a corresponding salt.

### Step 3: Compare the Acidity of Phenol and Benzoic Acid
- **Phenol**: It is a weak acid. When dissolved in water, it partially ionizes to form phenoxide ions (C₆H₅O⁻).
- **Benzoic Acid**: It is a stronger acid compared to phenol. It ionizes more completely in water to form benzoate ions (C₆H₅COO⁻).

### Step 4: Reaction with Sodium Carbonate
- **Benzoic Acid**: Since it is a stronger acid, it will react with sodium carbonate:
\[ \text{C}_6\text{H}_5\text{COOH} + \text{Na}_2\text{CO}_3 \rightarrow \text{C}_6\text{H}_5\text{COO}^- \text{Na}^+ + \text{H}_2\text{CO}_3 \]
This reaction produces carbon dioxide gas, which can be observed as effervescence.

- **Phenol**: As a weak acid, phenol does not react with sodium carbonate:
\[ \text{C}_6\text{H}_5\text{OH} + \text{Na}_2\text{CO}_3 \text{ (no reaction)} \]
Therefore, no effervescence will be observed with phenol.

### Step 5: Conclusion on the Assertion
Since benzoic acid reacts with sodium carbonate and phenol does not, we can distinguish between the two using sodium carbonate. Thus, the assertion is correct.

### Step 6: Understand the Reason
The reason states that benzoic acid is a stronger acid than phenol, which is true. The strength of an acid is determined by the stability of its conjugate base. Benzoate ions are more stable than phenoxide ions due to better charge delocalization.

### Step 7: Conclusion on the Reason
The reason correctly explains why benzoic acid reacts with sodium carbonate while phenol does not. Therefore, the reason is also correct.

### Final Conclusion
Both the assertion and the reason are true, and the reason is the correct explanation of the assertion.

### Summary of the Solution
- **Assertion**: True
- **Reason**: True
- **Conclusion**: Both assertion and reason are correct, and the reason explains the assertion.

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