`C_(6)H_(5)-C-=C-CH_(3)underset(H_(2)SO_(4))overset(HgSO_(4))rarrA`

Options

A.
B.
C. (C)`C_(6)H_(5)-underset(OH)underset(|)C=CHCH_(3)`
D. `(D)C_(6)H_(5)-CH=underset(OH)underset(|)C-CH_(3)`

Answer

To solve the given reaction of `C6H5-C≡C-CH3` in the presence of `HgSO4` and `H2SO4`, we will follow these steps:

### Step 1: Identify the Reactants
The reactant is `C6H5-C≡C-CH3`, which is phenylacetylene (a terminal alkyne).

### Step 2: Understand the Reaction Conditions
The reaction is carried out in the presence of `HgSO4` and `H2SO4`. This indicates that we are performing an acid-catalyzed hydration of the alkyne. The `HgSO4` acts as a catalyst to facilitate the addition of water across the triple bond.

### Step 3: Add Water Across the Triple Bond
In the presence of `H2SO4`, water (H2O) will add across the triple bond of the alkyne. The reaction proceeds via the formation of an intermediate vinyl cation. The addition of water will result in the formation of an enol.

The structure after this step will be:
```
C6H5-C(OH)=C-CH3
```
This is the enol form.

### Step 4: Tautomerization to Ketone
The enol formed is not stable and will undergo tautomerization to form a more stable ketone. The hydrogen from the hydroxyl group will migrate to the adjacent carbon, resulting in the formation of a carbonyl group (C=O).

The final product after tautomerization will be:
```
C6H5-C(=O)-CH2-CH3
```
This compound is known as propiophenone.

### Step 5: Final Product Identification
The final product A is identified as propiophenone, which can be represented as:
```
C6H5-C(=O)-CH2-CH3
```

### Summary of the Reaction
The reaction of phenylacetylene with `HgSO4` and `H2SO4` leads to the formation of propiophenone through hydration and subsequent tautomerization.

### Final Answer
The product A is **propiophenone**.

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