In the given reaction
`C_(6)H_(5)-overset(O)overset(||)(C)-CH_(3)overset([X])rarrC_(6)H_(5)-CH_(2)-CH_(3)`
[X] will be -

Options

A. `LiAIH_(4)`
B. `NaBH_(4)`
C. `Bu_(3)SnH`
D. `NH_(2)-NH_(2)//overset(Theta)(O)H`

Answer

To solve the given question, we need to identify the reagent [X] that will convert acetophenone (C₆H₅-C(=O)-CH₃) to ethylbenzene (C₆H₅-CH₂-CH₃).

### Step-by-step Solution:

1. **Identify the Reactants and Products:**
- The reactant is acetophenone, which has the structure C₆H₅-C(=O)-CH₃.
- The product is ethylbenzene, which has the structure C₆H₅-CH₂-CH₃.

2. **Understand the Reaction Type:**
- The reaction involves the reduction of the carbonyl group (C=O) in acetophenone to a methylene group (CH₂).
- This transformation indicates that we need a reducing agent capable of converting the carbonyl group into a methylene group.

3. **Identify the Suitable Reducing Agent:**
- A common reagent that can achieve this transformation is Lithium Aluminum Hydride (LiAlH₄).
- However, for the specific transformation from a ketone to an alkane (in this case, from acetophenone to ethylbenzene), we can also use a combination of zinc (Zn) and hydrochloric acid (HCl), known as Clemmensen reduction.

4. **Conclusion:**
- Therefore, the reagent [X] that will facilitate this reaction is **Zn/HCl** (Clemmensen reduction).

### Final Answer:
[X] will be **Zn/HCl**.

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