A : When 3,3-dimethyl butan - 2 - ol is heated in presence of concentrated `H_(2)SO_(4)` then 2, 3-dimethyl but -2-ene is formed as major product .
R : In this reaction , carbocation is formed as an intermediate

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1)
B. If both Assertion & Reason are true but the reason is not the correct explanation of the assertion, then mark (2)
C. If Assertion is true statement but Reason is false , then mark (3)
D. If both Assertion and Reason are false statements , then mark (4)

Answer

To solve the assertion-reason question regarding the reaction of 3,3-dimethylbutan-2-ol with concentrated H₂SO₄, we will analyze both the assertion (A) and the reason (R) step by step.

### Step 1: Understanding the Assertion (A)
The assertion states that when 3,3-dimethylbutan-2-ol is heated in the presence of concentrated H₂SO₄, 2,3-dimethylbut-2-ene is formed as the major product.

- **Structure of 3,3-dimethylbutan-2-ol**:
- The compound has four carbon atoms (butane) with a hydroxyl (OH) group on the second carbon and two methyl (CH₃) groups on the third carbon.

- **Heating with H₂SO₄**:
- Concentrated sulfuric acid acts as a dehydrating agent, facilitating the elimination of water (H₂O) and leading to the formation of an alkene.

### Step 2: Reaction Mechanism
1. **Protonation of the Alcohol**:
- The hydroxyl group (OH) of 3,3-dimethylbutan-2-ol gets protonated by H₂SO₄, converting it into a better leaving group (water).

2. **Formation of Carbocation**:
- The protonation leads to the loss of water, resulting in the formation of a carbocation. In this case, a secondary carbocation is formed initially.

3. **Carbocation Rearrangement**:
- The secondary carbocation can undergo rearrangement to form a more stable tertiary carbocation by a methyl shift from the adjacent carbon.

4. **Elimination to Form Alkene**:
- The final step involves the elimination of a proton (H⁺) from a neighboring carbon, leading to the formation of a double bond (alkene).

### Step 3: Identifying the Major Product
- The major product formed is 2,3-dimethylbut-2-ene, which is more stable due to the presence of more alkyl groups around the double bond (according to Zaitsev's rule).

### Step 4: Understanding the Reason (R)
The reason states that in this reaction, a carbocation is formed as an intermediate.

- **Correctness of the Reason**:
- This statement is true, as the formation of a carbocation is a crucial step in the dehydration mechanism of alcohols.

### Conclusion
- Both the assertion (A) and the reason (R) are true.
- The reason (R) correctly explains the assertion (A) because the formation of a carbocation is essential for the elimination reaction leading to the alkene product.

### Final Answer
- **Assertion (A)**: True
- **Reason (R)**: True
- **Explanation**: R is the correct explanation of A.