In which of the following compound `O^18` exchange can be observed on keeping it in `H_(2)O^(18)`

Options

A.
B.
C.
D.

Explanation

To solve the problem of which compound can undergo O^18 exchange when kept in H2O^18, we will analyze each of the given compounds and their potential for isotopic exchange with the labeled water.

### Step-by-Step Solution:

1. **Understanding Isotopic Exchange**:
- Isotopic exchange involves the replacement of one isotope of an element with another isotope of the same element. In this case, we are looking for the exchange of O^16 with O^18.

2. **Identifying the Compounds**:
- We have four compounds to analyze:
- A: Carboxylic Acid
- B: Benzene Sulfonic Acid
- C: Phenol
- D: Ketone

3. **Analyzing Each Compound**:
- **Carboxylic Acid**:
- Carboxylic acids can participate in exchange reactions, but they typically do not form stable intermediates with water that would lead to O^18 exchange.

- **Benzene Sulfonic Acid**:
- Similar to carboxylic acids, benzene sulfonic acids do not readily undergo isotopic exchange with water due to the stability of the sulfonate group.

- **Phenol**:
- Phenol can undergo some degree of exchange, but it does not form a stable intermediate that would facilitate O^18 exchange with water.

- **Ketone**:
- Ketones can form hydrates in the presence of water. The reaction can be represented as:
\[ R_2C=O + H_2O \rightarrow R_2C(OH)2 \]
- In this reaction, the oxygen from H2O^18 can replace the oxygen in the carbonyl group of the ketone, leading to O^18 exchange.

4. **Conclusion**:
- Among the compounds analyzed, the ketone is the only one that can undergo O^18 exchange when kept in H2O^18 due to the formation of a hydrate.

### Final Answer:
The compound that can undergo O^18 exchange when kept in H2O^18 is **Option D: Ketone**.