Acid-catalysed hydration oxymercuration-demercu-ration, and hydroboration oxidation reaction will give the same product with:

Options

A. a.But-2-ene
B. b.But-1-ene
C. c.
D. d.

Explanation

To determine which alkene will yield the same product from acid-catalyzed hydration, oxymercuration-demercuration, and hydroboration-oxidation reactions, we need to analyze the mechanisms of these reactions and how they apply to the given alkenes.

### Step-by-Step Solution:

1. **Understand the Reactions**:
- **Acid-Catalyzed Hydration**: This reaction adds water across the double bond of the alkene. The OH group attaches to the more substituted carbon (Markovnikov's rule).
- **Oxymercuration-Demercuration**: This involves the addition of mercury acetate (Hg(OAc)2) followed by reduction. It also follows Markovnikov's rule, where the OH group attaches to the more substituted carbon.
- **Hydroboration-Oxidation**: This reaction involves the addition of borane (BH3) followed by oxidation. It follows anti-Markovnikov's rule, where the OH group attaches to the less substituted carbon.

2. **Identify the Alkene**:
- We need to find an alkene where both Markovnikov and anti-Markovnikov products yield the same alcohol. This typically occurs when the alkene is symmetrical, meaning both carbons involved in the double bond have the same number of hydrogen atoms.

3. **Evaluate the Options**:
- **Option A: 2-Butene**: This is a symmetrical alkene. In both reactions, the OH group will attach to the same carbon, yielding 2-butanol.
- **Option B: 1-Butene**: This is not symmetrical. The products will differ between the two reactions.
- **Option C: Cyclopentene with a side chain**: The products will differ due to the asymmetry of the double bond.
- **Option D: Cyclopentene with a methyl side chain**: Similar to option C, the products will differ.

4. **Conclusion**:
- The only alkene that gives the same product from both oxymercuration-demercuration and hydroboration-oxidation is **2-butene** (option A), which yields 2-butanol in both cases.

### Final Answer:
**Option A: 2-Butene** gives the same product in acid-catalyzed hydration, oxymercuration-demercuration, and hydroboration-oxidation reactions.