The compound X, in the reaction, is
`X overset(CH_(3)Mgl)to Y overset("hydrolysis")to Mg(OH)I+ CH_(3)COOH`

Options

A. `CH_(3)CHO`
B. `CO_(2)`
C. `(CH_(3))_(2)CO`
D. `HCHO`

Explanation

To solve the problem, we need to identify the compound X in the reaction:

\[ X \overset{(CH_3)MgI}{\rightarrow} Y \overset{\text{hydrolysis}}{\rightarrow} Mg(OH)I + CH_3COOH \]

### Step-by-Step Solution:

1. **Identify the Grignard Reagent**: The reaction begins with a Grignard reagent, which is represented as \( (CH_3)MgI \). This indicates that the compound X must be a carbonyl compound that can react with the Grignard reagent.

2. **Determine the Nature of Compound Y**: After the reaction with the Grignard reagent, we obtain compound Y. The hydrolysis of Y produces \( Mg(OH)I \) and \( CH_3COOH \) (acetic acid). This suggests that Y must be a magnesium salt of a carboxylic acid.

3. **Formulate the Reaction**: The Grignard reagent \( (CH_3)MgI \) will react with a carbonyl compound to form an alcohol. The carbonyl compound that would yield acetic acid upon hydrolysis is carbon dioxide \( CO_2 \). Therefore, we can deduce that:

\[ (CH_3)MgI + CO_2 \rightarrow Y \]

This reaction forms a magnesium salt of acetic acid.

4. **Hydrolysis of Y**: The hydrolysis of Y (the magnesium salt of acetic acid) will yield \( Mg(OH)I \) and \( CH_3COOH \):

\[ Y \overset{\text{hydrolysis}}{\rightarrow} Mg(OH)I + CH_3COOH \]

5. **Conclusion**: From the above steps, we conclude that the compound X is \( CO_2 \) (carbon dioxide).

### Final Answer:
The compound X is \( CO_2 \).

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