When propyne is treated with aqueous `H_2SO_4` in the presence of `HgSO_4`, the major product is:

Options

A. (a) Propanal
B. (b) Propyl hydrogen sulphate
C. (c) Acetone
D. (d) Propanol

Explanation

To solve the problem of what major product is formed when propyne is treated with aqueous H₂SO₄ in the presence of HgSO₄, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**:
- The reactant is propyne (C₃H₄), which has the structure CH₃-C≡CH.
- The reagents are aqueous sulfuric acid (H₂SO₄) and mercuric sulfate (HgSO₄).

2. **Protonation of the Alkyne**:
- The triple bond in propyne is nucleophilic and will attack a proton (H⁺) from the sulfuric acid.
- This results in the formation of a carbocation intermediate. The more stable carbocation will be formed, which is the one at the more substituted carbon.
- The reaction can be represented as:
\[ CH₃-C≡CH + H⁺ \rightarrow CH₃-C^+(H)-CH₂ \]

3. **Nucleophilic Attack by Water**:
- Water (H₂O) acts as a nucleophile and attacks the carbocation, leading to the formation of an alcohol.
- The reaction can be represented as:
\[ CH₃-C^+(H)-CH₂ + H₂O \rightarrow CH₃-C(OH)(H)-CH₂ \]

4. **Deprotonation**:
- The alcohol formed will lose a proton (H⁺) to form a double bond, resulting in an enol.
- The reaction can be represented as:
\[ CH₃-C(OH)(H)-CH₂ \rightarrow CH₃-C(=CH₂)-OH \]

5. **Keto-Enol Tautomerization**:
- The enol can undergo tautomerization to form a ketone. The enol form is less stable than the keto form.
- The keto form of the product is acetone (CH₃-CO-CH₃).
- The reaction can be represented as:
\[ CH₃-C(=CH₂)-OH \rightarrow CH₃-CO-CH₃ \]

6. **Final Product**:
- The major product of the reaction is acetone (CH₃COCH₃).

### Conclusion:
The major product formed when propyne is treated with aqueous H₂SO₄ in the presence of HgSO₄ is acetone (option C).