`Ph-CH_2-C-=CHunderset(Y)overset(X)hArrPh-C-=C-CH_3`.
The reagents X and Y respectively are

Options

A. Lindlar catalyst , `NaNH_2`
B. `NaNH_2` and alc . KOH
C. Pt catalyst , Wilkison's catalyst
D. Alc. KOH and `NaNH_2`

Answer

To solve the problem, we need to identify the reagents X and Y that facilitate the transformation of the compound Ph-CH₂-C≡CH into Ph-C≡C-CH₃.

### Step-by-Step Solution:

1. **Identify the Starting Material**:
The starting compound is Ph-CH₂-C≡CH, which is a terminal alkyne (with a triple bond between the second and third carbon).

2. **Identify the Target Compound**:
The target compound is Ph-C≡C-CH₃, which is a terminal alkyne with the triple bond between the first and second carbon atoms.

3. **Understand the Reaction Type**:
The transformation from a terminal alkyne to another terminal alkyne indicates that we are likely dealing with an isomerization reaction. In this case, we are moving the position of the triple bond.

4. **Determine Reagent Y**:
To facilitate the isomerization of the alkyne, we can use a strong base. One common reagent for this purpose is sodium amide (NaNH₂). This reagent can deprotonate the terminal alkyne and allow for the rearrangement of the triple bond.

5. **Determine Reagent X**:
After the isomerization step, we need to ensure that the reaction can proceed in the desired direction. Alcoholic KOH is a suitable reagent for promoting the isomerization of alkynes. It can help in the formation of the internal alkyne from the terminal alkyne.

6. **Final Conclusion**:
Therefore, the reagents X and Y respectively are:
- X: Alcoholic KOH
- Y: Sodium amide (NaNH₂)

### Final Answer:
- X = Alcoholic KOH
- Y = Sodium amide (NaNH₂)