A compound [A] has the formula `C_(4)H_(8)O_(2)`. When reacted with a Grignard reagent, `CH_(3)MgBr`, it takes up two molecules of it and upon acidification gives an alcohol [B]. The alcohol on reacting with Lucas reagent gives white coludiness on standing for sometime. When the alochol is oxidised, a compound [C] is produced with a pleasant smell. It neither reacts with Tollen's reagent, nor with Fehling's reagent.
The compound [A] is

Options

A. an ester
B. a saturated carboxylic acid
C. an unsaturated carboxylic acid
D. an `alpha`-diketone.

Explanation

To determine the compound [A] with the formula \( C_4H_8O_2 \), we will analyze the information provided step by step.

### Step 1: Identify the structure of compound [A]
Given the molecular formula \( C_4H_8O_2 \), we can deduce that the compound is likely a carboxylic acid or an ester. Since it reacts with a Grignard reagent, it is more likely to be an ester.

### Step 2: Reaction with Grignard Reagent
The compound [A] reacts with the Grignard reagent \( CH_3MgBr \) and takes up two molecules of it. This suggests that [A] is an ester, as esters react with Grignard reagents to form alcohols.

The reaction can be represented as follows:
\[ RCOOR' + 2 CH_3MgBr \rightarrow RCO-MgBr + R'OMgBr \]
Upon acidification, this will yield a secondary alcohol.

### Step 3: Formation of Alcohol [B]
The alcohol [B] formed after the reaction with Grignard reagent is a secondary alcohol. Since the reaction takes up two equivalents of the Grignard reagent, it indicates that the original compound [A] must be a diester or a simple ester that leads to a secondary alcohol upon hydrolysis.

### Step 4: Reacting with Lucas Reagent
The alcohol [B] gives white cloudiness upon reacting with Lucas reagent, indicating that it is a secondary alcohol. Lucas reagent is used to differentiate between primary, secondary, and tertiary alcohols, and secondary alcohols react to form a cloudy solution.

### Step 5: Oxidation of Alcohol [B]
When alcohol [B] is oxidized, it produces compound [C] with a pleasant smell. This suggests that compound [C] is likely a ketone or an ester, as both can have pleasant odors.

### Step 6: Non-reactivity with Tollen's and Fehling's Reagents
The fact that compound [C] does not react with Tollen's reagent or Fehling's reagent indicates that it is not an aldehyde, as these reagents are used to test for aldehydes. This further supports the idea that compound [C] is a ketone or an ester.

### Conclusion
Based on the above deductions, the compound [A] is likely to be **butanoate** (an ester), specifically **ethyl acetate** (ethyl ethanoate), which has the structure:
\[ CH_3COOCH_2CH_3 \]

### Final Answer
The compound [A] is **ethyl acetate**.

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