Assertion: Aquated copper(I) cation undergoes disproportionation as:
`2Cu^(+)(aq) to Cu^(2+)(aq)+Cu`
Reason: Hydration energy of `Cu^(2+)` is higher than that of `Cu^(+)` which compensates second ionisation energy of Cu.

Options

A. If both assertion and reason are true and the reason is the correct explanation of assertion
B. If both assertion and reason are true and the reason is not the correct explanation of assertion
C. If assertion is false but reason is true
D. If assertion is true but the reason is false

Answer

To solve the question, we will analyze the assertion and reason statements step by step.

### Step 1: Analyze the Assertion
The assertion states that the aquated copper(I) cation undergoes disproportionation as follows:
\[ 2 \text{Cu}^+(aq) \rightarrow \text{Cu}^{2+}(aq) + \text{Cu} \]

**Explanation**:
- Copper(I) ion (\(\text{Cu}^+\)) is known to be less stable in aqueous solution compared to copper(II) ion (\(\text{Cu}^{2+}\)).
- Due to this instability, \(\text{Cu}^+\) tends to disproportionate into \(\text{Cu}^{2+}\) and elemental copper (\(\text{Cu}\)).
- Therefore, the assertion is **true**.

### Step 2: Analyze the Reason
The reason states that the hydration energy of \(\text{Cu}^{2+}\) is higher than that of \(\text{Cu}^+\), which compensates for the second ionization energy of copper.

**Explanation**:
- Hydration energy refers to the energy released when ions are surrounded by water molecules.
- The \(\text{Cu}^{2+}\) ion has a higher charge density than \(\text{Cu}^+\), leading to a greater attraction to water molecules and thus a higher hydration energy.
- This higher hydration energy compensates for the energy required to remove the second electron from copper, making the formation of \(\text{Cu}^{2+}\) favorable.
- Therefore, the reason is also **true** and correctly explains the assertion.

### Step 3: Conclusion
Both the assertion and the reason are true, and the reason correctly explains the assertion.

### Final Answer
Both assertion and reason are true, and the reason is the correct explanation of the assertion. Therefore, the answer is option 1.

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