Which of the given statements is incorrect?

Options

A. Peroxide effect proceeds via free radical chain mechanism
B. Peroxide effect is not observed in case of HCI
C. Tertiary carbocation is less stable than secondary carbocation
D. Kharasch effect is applicable for unsymmetrical alkenes

Answer

To determine which of the given statements is incorrect, we will analyze each statement one by one.

### Step 1: Analyze the first statement
**Statement 1:** The peroxide effect proceeds via free radical chain mechanism.

- The peroxide effect, also known as the Kharash effect, occurs when the addition of HBr to an unsymmetrical alkene takes place contrary to Markovnikov's rule in the presence of peroxides. This reaction proceeds through a free radical mechanism, starting with the homolytic cleavage of the peroxide to generate free radicals.

**Conclusion:** This statement is **correct**.

### Step 2: Analyze the second statement
**Statement 2:** The peroxide effect is not observed in case of HCl.

- The peroxide effect specifically applies to the addition of HBr to unsymmetrical alkenes and is not observed with HCl or HI.

**Conclusion:** This statement is **correct**.

### Step 3: Analyze the third statement
**Statement 3:** The tertiary carbocation is less stable than the secondary carbocation.

- In organic chemistry, the stability of carbocations increases with the number of alkyl groups attached to the positively charged carbon. Tertiary carbocations are more stable than secondary carbocations due to the +I effect (inductive effect) of the alkyl groups, which helps to stabilize the positive charge.

**Conclusion:** This statement is **incorrect**.

### Step 4: Analyze the fourth statement
**Statement 4:** The Kharash effect is applicable for the unsymmetrical alkene.

- The Kharash effect indeed applies to unsymmetrical alkenes, where the addition of HBr in the presence of peroxides leads to the formation of products that do not follow Markovnikov's rule.

**Conclusion:** This statement is **correct**.

### Final Answer
The incorrect statement is **Statement 3**: "The tertiary carbocation is less stable than the secondary carbocation."

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