Assertion: Aryl halides cannot be prepared by replacement of hydroxyl group of phenol by halogen atom.
Reason: Phenols react with halogen acids violently.

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 assetion is true but reason is false.
D. If both assertion and reason are false.

Explanation

To solve the question regarding the assertion and reason about aryl halides and phenols, let's break it down step by step.

### Step 1: Understand the Assertion
The assertion states that "Aryl halides cannot be prepared by replacement of the hydroxyl group of phenol by a halogen atom."

- **Explanation**: Aryl halides are compounds where a halogen atom is directly bonded to an aromatic ring. In phenol, the hydroxyl group (-OH) is attached to the aromatic ring. The assertion claims that we cannot simply replace this -OH group with a halogen atom (like Cl or Br) to form an aryl halide.

### Step 2: Analyze the Reason
The reason given is "Phenols react with halogen acids violently."

- **Explanation**: This statement implies that phenols can react with halogen acids (like HCl or HBr) to form halogenated products. However, the nature of the bond between the oxygen and carbon in phenol is important. The oxygen atom has lone pairs that participate in resonance, giving the carbon-oxygen bond a partial double bond character. This makes it difficult to break this bond during a substitution reaction.

### Step 3: Resonance in Phenol
Phenol exhibits resonance due to the lone pairs on the oxygen atom. This resonance stabilizes the molecule but also makes the carbon-oxygen bond stronger.

- **Explanation**: The resonance structures of phenol show that the carbon-oxygen bond has partial double bond character, which means that breaking this bond to replace -OH with a halogen is not feasible.

### Step 4: Conclusion on Assertion and Reason
Based on the analysis:

- The assertion is **true**: Aryl halides cannot be prepared by simply replacing the -OH group in phenol because of the strong carbon-oxygen bond due to resonance.
- The reason is **false**: While phenols do react with halogen acids, the assertion about the difficulty of replacing the -OH group is not due to this violent reaction, but rather due to the stability of the carbon-oxygen bond.

### Final Answer
- **Assertion**: True
- **Reason**: False