Assertion (A): The dissolution of gases in water is always an endothermic process.
Reason (R ) : The dissolution of gases in water proceed with a negative value of `DeltaS`.

Options

A. If both `(A)` and `(R )` are correct, and `(R )` is the correct explanation of `(A)`.
B. If both `(A)` and `(R )` are correct, but `(R )` is not the correct explanation of `(A)`.
C. If `(A)` is correct, but `(R )` is incorrect.
D. If `(A)` is correct, but `(R )` is correct.

Explanation

To analyze the assertion and reason provided in the question, we will break down the concepts involved step by step.

### Step-by-Step Solution:

1. **Understanding the Assertion (A)**:
- The assertion states that "The dissolution of gases in water is always an endothermic process."
- An endothermic process is one that absorbs heat from the surroundings.
- When gases dissolve in water, energy is required to break the intermolecular forces between water molecules and to accommodate the gas molecules. This means that the process often absorbs heat, making it endothermic.

2. **Evaluating the Reason (R)**:
- The reason states that "The dissolution of gases in water proceeds with a negative value of ΔS."
- ΔS represents the change in entropy, which is a measure of disorder in a system.
- When a gas dissolves in a liquid, the gas molecules become more ordered as they interact with the solvent molecules, which can lead to a decrease in entropy (negative ΔS).
- However, this is not universally true for all gases. Depending on the specific gas and conditions, the dissolution can lead to an increase in entropy (positive ΔS) as well.

3. **Conclusion**:
- The assertion is correct: the dissolution of gases in water is generally an endothermic process.
- The reason is incorrect: we cannot definitively say that the dissolution of gases always results in a negative ΔS, as it can vary based on the gas and conditions.
- Therefore, the correct answer is that the assertion is correct, but the reason is incorrect.

### Final Answer:
- Assertion (A) is correct.
- Reason (R) is incorrect.