`CH -= CH + H_2O underset(HgSO_4) overset(H_2SO_4) to X`. In the following reaction X is

Options

A. acetadehyde
B. propionaldehyde
C. ketone
D. ethanol

Explanation

To solve the question, we need to analyze the reaction of ethyne (C2H2) with water in the presence of sulfuric acid (H2SO4) and mercuric sulfate (HgSO4). Let's break down the steps:

### Step-by-Step Solution:

1. **Identify the Reactants**:
The reactants are ethyne (C2H2) and water (H2O).

2. **Understand the Role of Catalysts**:
The presence of H2SO4 and HgSO4 indicates that we are performing an acid-catalyzed hydration reaction. HgSO4 acts as a catalyst to facilitate the addition of water to the alkyne.

3. **Addition of Water**:
When ethyne reacts with water, the addition occurs according to Markovnikov's rule. This means that the hydrogen atom from water will attach to the carbon of the triple bond that has more hydrogen atoms (the terminal carbon), while the hydroxyl group (OH) will attach to the other carbon.

4. **Formation of Enol**:
The initial product of this reaction is an enol, which is an intermediate compound. In this case, the enol formed is CH3-CH=CHOH (vinyl alcohol).

5. **Tautomerization**:
The enol undergoes tautomerization, which is a structural rearrangement that converts the enol to a more stable form, which is a carbonyl compound (aldehyde or ketone). In this case, the enol tautomerizes to form acetaldehyde (CH3CHO).

6. **Final Product**:
The final product (X) after the reaction is acetaldehyde (CH3CHO).

### Conclusion:
Thus, the product X in the reaction CH≡CH + H2O (HgSO4, H2SO4) is acetaldehyde (CH3CHO).