Identify X in the sequence,
X `underset(2H_(2)O //H^(+))overset(1.CH_(3) "MgCl")(rarr) C_(5) H_(12) O underset(575K)overset(Cu)(rarr) C_(5)H_(10)`

Options

A. `CH_(3) - underset(O)underset(||)(C ) - CH_(2) - CH_(3)`
B. `CH_(3) CH_(2)CH_(2)`CHO
C. `(CH_(3))_(2)`CHCHO
D. `CH_(3)CH_(2)CH_(2)CH_(2)`OH

Explanation

To identify X in the given sequence, we need to analyze the reactions step by step.

### Step 1: Understanding the Product C5H12O
We start with the product C5H12O, which can be either an alcohol or an ether. Given that the final product after the reaction with copper at high temperature is C5H10 (an alkene), it is more likely that C5H12O is an alcohol.

### Step 2: Determining the Degree of Unsaturation
To confirm the type of compound, we can calculate the degree of unsaturation using the formula:
\[ \text{Degree of Unsaturation} = \frac{C + 1 - H + X - N}{2} \]
Where:
- C = number of carbon atoms = 5
- H = number of hydrogen atoms = 12
- X = number of halogens = 0
- N = number of nitrogen atoms = 0

Substituting the values:
\[ \text{Degree of Unsaturation} = \frac{5 + 1 - 12 + 0 - 0}{2} = \frac{-6}{2} = 0 \]
A degree of unsaturation of 0 indicates that the compound is saturated, confirming that C5H12O is likely a saturated alcohol.

### Step 3: Reaction with Grignard Reagent
The next step involves the reaction of X with CH3MgCl (a Grignard reagent). Since we suspect that C5H12O is a tertiary alcohol, we can deduce that the compound X must be a ketone that can react with the Grignard reagent to form a tertiary alcohol.

### Step 4: Identifying the Ketone
To form a tertiary alcohol with five carbon atoms after the reaction with CH3MgCl, the ketone must have four carbon atoms. The simplest ketone with four carbon atoms is 2-butanone (CH3C(O)CH2CH3).

### Step 5: Hydrolysis and Final Product
After the reaction with the Grignard reagent and subsequent hydrolysis, we would obtain a tertiary alcohol, which upon heating with copper at 575 K would dehydrate to form an alkene, specifically C5H10.

### Conclusion
Thus, the compound X that leads to the formation of C5H12O upon reaction with CH3MgCl is 2-butanone (CH3C(O)CH2CH3).

### Final Answer
**X = 2-butanone (CH3C(O)CH2CH3)**

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