In the reaction sequence, [X] is ketone :
`[X] overset(KMnO_(4)//OH^(-)//Delta)rarrHOOC(CH_(2))_(3)-overset(CH_(3))overset(|)CH-COOH`
[X] will be :-

Options

A.
B.
C.
D.

Answer

To solve the problem, we need to determine the structure of the ketone [X] that, when treated with KMnO4 in the presence of OH- and heat (Δ), yields the product HOOC(CH2)3-CH(CH3)-COOH.

### Step-by-Step Solution:

1. **Identify the Product Structure**:
The product given is HOOC(CH2)3-CH(CH3)-COOH. This indicates that the product is a dicarboxylic acid with a total of 7 carbon atoms. The structure can be broken down as follows:
- Two carboxylic acid groups (HOOC).
- A straight chain of 3 methylene groups (CH2) connecting the two carboxylic acid groups.
- A methyl group (CH3) attached to the central carbon.

2. **Count the Carbons**:
Counting the carbon atoms in the product:
- 2 from the carboxylic acid groups (1 from each).
- 3 from the (CH2)3 chain.
- 1 from the central carbon (which has the methyl substituent).
- Total = 2 + 3 + 1 = 6 carbon atoms from the chain, plus 1 from the methyl group = 7 carbon atoms.

3. **Determine the Ketone Structure**:
Since the oxidation of a ketone leads to the cleavage of the carbon chain, we need to find a ketone that, when oxidized, will yield the above product. The ketone must have a structure that allows for the formation of two carboxylic acids upon oxidation.

4. **Consider Possible Ketones**:
The ketone must have a total of 7 carbon atoms. The possible structures can be:
- A ketone with a methyl group on one side and a longer carbon chain on the other.
- The oxidation of this ketone should lead to the cleavage of the carbon chain at the ketone position.

5. **Choose the Correct Option**:
From the options provided, we need to find a ketone that matches this description.
- Option B suggests cyclohexanone with a methyl group.
- When oxidized, this structure can lead to the formation of the desired product, as it has the correct number of carbon atoms and the necessary substituents.

6. **Conclusion**:
Therefore, the correct ketone [X] that will yield the product upon oxidation with KMnO4 is **option B**.

### Final Answer:
The ketone [X] is **option B**.