Which of the following alkene in acid catalysed hydration form `2-`methyl propan `-2-ol` ?

Options

A. `(CH_(3))_(2)CH=CH_(2)`
B. `CH_(3)CH=CH_(2)`
C. `CH_(3)-CH=CH-CH_(3)`
D. `CH_(3)-CH_(2)-CH=CH_(2)`

Explanation

To determine which alkene will form 2-methylpropan-2-ol upon acid-catalyzed hydration, we will analyze each option provided.

### Step-by-Step Solution:

1. **Identify the Alkenes**: We have four alkenes to consider:
- A: CH3-CH=CH2
- B: CH3-CH=CH-CH2
- C: CH3-CH=CH-CH3
- D: CH3-CH2-CH=CH2

2. **Apply Acid-Catalyzed Hydration**: In acid-catalyzed hydration, the alkene reacts with water in the presence of an acid catalyst. According to Markovnikov's rule, the hydroxyl group (OH) will attach to the carbon with the greater number of hydrogen atoms, while the hydrogen (H) will attach to the carbon with fewer hydrogen atoms.

3. **Analyze Each Alkene**:
- **Option A (CH3-CH=CH2)**:
- The double bond between the second and third carbon will break.
- OH will attach to the second carbon (more substituted), and H will attach to the third carbon.
- Product: CH3-CHOH-CH3 (which is 2-propanol, not 2-methylpropan-2-ol).

- **Option B (CH3-CH=CH-CH2)**:
- The double bond between the second and third carbon will break.
- OH will attach to the second carbon, and H will attach to the third carbon.
- Product: CH3-CHOH-CH2-CH3 (which is not 2-methylpropan-2-ol).

- **Option C (CH3-CH=CH-CH3)**:
- The double bond between the second and third carbon will break.
- OH can attach to either the second or third carbon since it is symmetrical.
- Product: CH3-CHOH-CH2-CH3 (which is not 2-methylpropan-2-ol).

- **Option D (CH3-CH2-CH=CH2)**:
- The double bond between the third and fourth carbon will break.
- OH will attach to the third carbon (more substituted), and H will attach to the fourth carbon.
- Product: CH3-CH2-CHOH-CH3 (which is 2-methylpropan-2-ol).

4. **Conclusion**: After analyzing all options, we find that **Option D** is the correct answer as it forms 2-methylpropan-2-ol.

### Final Answer:
The alkene that forms 2-methylpropan-2-ol upon acid-catalyzed hydration is **Option D: CH3-CH2-CH=CH2**.